Novel solvents and methods of use for the removal of CO2 from flue gas, natural gas, hydrogen gas, synthesis gas, and other process and waste gas streams are provided. The solvent contains an alkali salt such as potassium carbonate and a polyamine such as piperazine (PZ) where the polyamine concentration is at least 1.5 equivalents/Kg H2O and the alkali salt concentration is at least 0.5 equivalents/Kg H2O. The preferred alkali salt/polyamine ratio is from approximately 1:2 to 2:1, and no additional alcohol is required for solubilizing the PZ. This chemical solvent and method of use provides efficient and effective removal of CO2 from gaseous streams and other sources.

The effects of CO2 emissions on global climate are driving a need to develop cost-effective technology for CO2 capture from fossil fuel combustion and other point sources. Extensive programs already in place are beginning to demonstrate the economic and technical feasibility of sequestering CO2 by approaches such as injection in underground reservoirs (Bergman, P. D., E. M. Winter, and Z-Y. Chen, "Disposal of Power Plant CO2 in Depleted Oil and Gas Reservoirs in Texas," presented at the Third International Conference on Carbon Dioxide Removal, Cambridge, Mass., Sep. 9-11, 1996) and disposal in the deep ocean (Fujioka, Y. et al., "Cost Comparison of Various CO2 Ocean Disposal Options," presented at the Third International Conference on Carbon Dioxide Removal, Cambridge, Mass., Sep. 9-11, 1996).
CO2 is emitted in large quantities from fuel combustion by mobile and stationary sources. CO2 capture/sequestration will be most effective if applied to large stationary sources. The largest single sources of CO2 are conventional coal-fired power plants that represent 30 to 40% of the CO2 emissions in the U.S. Technology developed for such sources should also be applicable to CO2 capture from gas and oil fired boilers, combined cycle power plants, coal gasification, and hydrogen plants. Absorption/stripping is suitable for both existing and new boilers. Specifically, it can be used with existing coal-fired boilers, especially if they already have scrubbers for SO2-abatement. However, this process can be expensive, potentially increasing the cost of electricity by 50%; therefore, technology improvements to reduce operating costs are desirable.
The use of organic solvents or aqueous solutions of organic solvents for the absorption/stripping process is well known. Alkanolamine absorption/stripping is one proven and effective technology for CO2 capture from gas. The first generation of this technology uses aqueous solutions of monoethanolamine (MEA). The energy consumption of this system is high, typically taking 15 to 30% of the power plant output (Herzog, H., E. Drake, & E. Adams, "CO2 Capture, Reuse, and Storage Technologies for Mitigating Global Climate Change," final rept, DOE Order No. DE-AF22-96PC01257, 1997). Advances in this technology have provided other alkanolamine solvents for CO2 treating in various industries. Monoethanolamine (MEA), diethanolamine (DEA), and the hindered amine AMP are used alone in an aqueous solution. Typical solvent blends include a methyldiethanolamine (MDEA) solution promoted by piperazine or other secondary amines.
Potassium carbonate and other solvents are commonly promoted by DEA or other reactive amines. These amines are provided in catalytic amounts and are used to improve the absorption characteristics of the solvent. Patents describing these solvents and processes include U.S. Pat. Nos. 4,094,957, 4,112,050, 4,217,237, 4,336,233, 4,581,209, 5,853,680, 6,036,931, 6,337,059 and 6,416,568
U.S. Pat. No. 4,336,233, which provides a solvent system combining MDEA and piperazine as an absorption accelerator, recognized that piperazine could be used alone in an aqueous system. Similarly, U.S. Pat. No. 6,337,059 provides a solvent system with greater than 1 M piperazine and MDEA where greater concentrations of piperazine improves the absorption performance of the solvent. However, piperazine concentration of greater than about 1.3 M are not usable because the piperazine precipitates out of the solution. Additionally, piperazine is highly volatile, limiting the practicality of this solvent.
U.S. Pat. No. 6,436,174 provides a solvent system in which certain concentrations of a nitrogen heterocycle such as piperazine can be used in combination with a monohydric or polyhydric alcohol. That disclosure finds that the solubility of the nitrogen heterocycle in the presence of a monohydric or polyhydric alcohol is generally markedly higher than the solubility of the nitrogen heterocycle alone. U.S. Pat. No. 6,436,174 does not, however, teach that a solvent system with a high concentration of an alkali salt will increase the solubility of a polyamine and does not provide suitable ranges of solvent components that would be effective to create a solvent that can efficiently remove CO2 from a gas stream.
It would be advantageous to provide an organic solvent for removal of CO2 from gas streams having faster reaction rates, acceptable volatility, and a low heat of absorption that will allow a reduction in cost for the absorption/stripping process. It would also be advantageous to provide a solvent that more closely approaches reversible absorption and stripping, which will particularly benefit operations with high CO2 concentrations.
Embodiments of the present invention contemplate a method of removing CO2 from a gaseous stream including: contacting a gaseous stream with a solution wherein the solution is formed by combining: a primary or secondary polyamine having an amine concentration of at least 3.0 equivalents/Kg water, an alkali salt having a concentration of at least 1.0 equivalents/Kg water, and water; whereby the contact removes CO2 from the gaseous stream; and regenerating the solution.
In another embodiment, a composition is provided wherein the composition is formed by combining: a piperazine derivative having a concentration of at least 3.0 equivalents/Kg water; and a potassium salt having a concentration of at least 1.0 equivalents/Kg water, water,
wherein the ratio of equivalents of alkali salt to equivalents of the piperazine derivative is 0.3-3.0. The piperazine derivative may be piperazine. The potassium salt may be a potassium alkali salt such as potassium carbonate, potassium bicarbonate, potassium bisulfide, or potassium hydroxide. The ratio of equivalents of alkali salt to equivalents of piperazine derivative may be 0.5-2.0, 0.8-1.3, or 0.9-1.1. The concentrations of the piperazine derivative and alkali salt are preferably between 3.0 and 8.0 equivalents/Kg H2O, or between 4.0 and 6.0 equivalents/Kg H2O. In one embodiment, the concentration of the piperazine derivative is approximately 5.0 equivalents/Kg H2O and the concentration of the alkali salt is approximately 5.0 equivalents/Kg H2O. The composition may further include an antioxidant, a corrosion inhibitor, a flocculation aid, or a mixture thereof.
Yet another embodiment of the current invention includes a method of removing CO2 from a gaseous stream including: contacting a gaseous stream with a solution wherein the solution is formed by combining: a primary or secondary polyamine having an amine concentration of at least 5.1 equivalents/Kg water, an alkali salt having a concentration of at least 5.1 equivalents/Kg water, and water; whereby the contact removes CO2 from the gaseous stream; and regenerating the solution. The concentration of the polyamine and the concentration of the alkali salt are may be least 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, or 8.0 equivalents/Kg water. Preferably, the concentrations are at least 5.5, 6.0, or 6.5 equivalents/Kg water. The concentration of the polyamine and the concentration of the alkali salt are preferably approximately equal; the concentrations may be approximately 5.1, 5.5, 6.0, 6.5, 7.0, 7.5, 8 or more equivalents/Kg H2O for both the polyamine and alkali salt. The concentrations will be limited by the solubility of the components at the temperature.
Another embodiment of the current invention includes a method of removing CO2 from a gaseous stream including: contacting a gaseous stream with a solution wherein the solution is formed by combining: a primary or secondary polyamine having an amine concentration of at least 3.0 equivalents/Kg water, an alkali salt having a concentration of at least 1.0 equivalents/Kg water, and water; wherein the solution contains less than 1% of a monohydric or polyhydric alcohol; whereby the contact removes CO2 from the gaseous stream; and regenerating the solution. In one embodiment, less than 1 percent by weight alcohol is added to the solution. In another embodiment, no alcohol is added.
Another embodiment of the current invention includes a method of removing CO2 from a gaseous stream including: contacting a gaseous stream with a solution wherein the solution is formed by combining: a piperazine derivative having an amine concentration of 3.0-10.0 equivalents/Kg water, an alkali salt having a concentration of 1.0-10.0 equivalents/Kg water, and water; wherein the concentration of the piperazine derivative and the concentration of the alkali salt are approximately equal; whereby the contact removes CO2 from the gaseous stream; and regenerating the solution. Preferably, the amine concentration and the alkali salt concentrations are between 3.0-8.0 equivalents/Kg water.
The polyamine may be a piperazine derivative such as piperazine, aminoethylpiperazine, hydroxyethylpiperazine, 3-(3-pyrrolidyl)piperidine, 2-(3-pyrrolidyl)piperazine, 3-(3-piperidyl)-piperidine, 3-(2-piperazinyl)piperidine, or 2-(2-piperazinyl)piperazine. The polyamine may be ethylenediamine, dimethyl ethylenediamine, pyrazolidine, imidazolidine, 2-(2-pyrrolidyl)-pyrrolidine, 2-(2-imidazolidyl)imidazolidine. Preferably, the amine moieties of the polyamine are not sterically hindered; preferably, at least one amine is not sterically hindered, or at least two amines are not sterically hindered, or three or more amines moieties on the polyamine are not sterically hindered, no amines located on the polyamine are sterically hindered. The alkali salt may be potassium carbonate, a sodium carbonate, a lithium carbonate, a bicarbonate salt, a bisulfide salt, or a hydroxide salt.
The temperature of the solution when contacting with the gaseous stream may be between approximately 25° C.-120° C. or more preferably approximately 40° C.-80° C. The rate constant for the reaction of CO2 with the piperazine derivative (KPZ) may be at least 25 m3/mol-s at 25° C., or at least 50 m3/mol-s at 25° C.
The regenerating may include heating CO2-rich solution, which may occur at a temperature of approximately 50° C.-150° C., approximately 60° C.-130° C., or approximately 100° C.-130° C. An additive such as an antifoaming agent, an antioxidant, a corrosion inhibitor (e.g. vanadium oxide or a chromate), a flocculation aid, or a mixture of two or more additives may be included as part of the solution.
The ratio of equivalents of alkali salt to equivalents of polyamine is preferably between 0.3-3.0, 0.5-2.0, 0.8-1.3, or most preferably between 0.9-1.1. The concentrations of the polyamine and alkali salt are preferably between 3.0 and 8.0 equivalents/Kg H2O or 4.0 and 6.0 equivalents/Kg H2O. The polyamine concentration and the alkali salt concentration may be at least 2.3 m. In one embodiment, the concentration of the polyamine is approximately 5.0 equivalents/Kg H2O and the concentration of the alkali salt is approximately 5.0 equivalents/Kg H2O.
In another embodiment, the method of removing CO2 from a gaseous stream may further include applying a water wash system, wherein the water wash system collects the polyamine from treated gaseous stream. The regeneration of the solution may occur in a vacuum stripper column, and the solution may be returned to contact with the gaseous stream after regeneration.
In one embodiment, the rate for the solvent-mediated removal of CO2 from the gaseous stream is at least 1.5 times the rate for CO2 removal in a method using an aqueous solution of 5.0-M monoethanolamine.
Other components of a gaseous stream, such as H2S or COS may also be removed by the method of the current invention. The gaseous stream may be from a coal-fired power plant, or it may be flue gas, natural gas, hydrogen gas, synthesis gas or a waste gas stream.
Embodiments of the present invention include a novel solvent and method of use for the removal of CO2 from flue gas, natural gas, hydrogen gas, synthesis gas, and other process and waste gas streams. The solvent may contain an alkali salt such as potassium carbonate and a polyamine such as piperazine (PZ) with an alkali salt/polyamine ratio from approximately 0.5 to 2 or more preferably 1 to 2, with the total concentration limited by the solid solubility of the polyamine or of the alkali salt, and will be at least 3.0 equivalents/Kg H2O PZ. No additional alcohols are required for increasing solubility of the PZ. This chemical solvent is designed to increase the rate of CO2 removal to improve the efficiency of the removal process.
As used herein, the term "synthesis gas" refers to gases comprising both hydrogen gas and carbon monoxide gas. The mole ratio of hydrogen to carbon monoxide may, but need not necessarily, be about one to one. Other inter materials such as nitrogen, carbon dioxide, hydrogen sulfide and COS and often found in synthesis gas.
As used herein the specification, "a" or "an" may mean one or more. As used herein in the claim(s), when used in conjunction with the word "comprising", the words "a" or "an" means one or more than one unless explicitly stated otherwise.
As used herein "another" may mean at least a second or more. As used herein the terms "approximately" and "about" both mean within 20% of the stated value or more particularly within 10% of the stated value.
A variety of alkali salts may be used in forming the solvent of the current invention. Alkali metals including but not limited to potassium, sodium and lithium may be used. They may be formed in any one of a variety of salts. These salts include, but are not limited to carbonate, bicarbonate, hydroxide, and bisulfide salts. One preferred salt is potassium carbonate. Other alkali salts include, potassium bicarbonate, potassium hydroxide, and potassium bisulfide.
Similarly, the lithium and sodium salts may be used, such as sodium carbonate and lithium carbonate.
Alternatively, a mixture of two or more salts may be used in place of a single alkali salt in the solvent. For example, potassium carbonate may be combined with sodium carbonate in a ratio of 1/10, 1/5, 3/10, 2/5, 1/1, 3/5, 7/10, 4/5, 9/10, 10/9, 5/4, 10/7, 5/3, 5/2, 5/1, 10/1 or any ratio therebetween. If a mixture of salts is used, the preferred concentration ratio of salt to polyamine is based on the total alkali salt concentration.
One advantage of a potassium carbonate solvent is that, because potassium sulfate and chloride may be useful as fertilizer, it will be easier to dispense of spent potassium carbonate solvent. Therefore, this solvent is more resistant to slippage of SO2 and HCl from an existing flue gas desulfurization system.
A variety of cyclic or linear, primary or secondary polyamines may be used as one component of the solvent of the current invention. The polyamine may be a piperazine derivative such as piperazine, aminoethylpiperazine, and hydroxyethylpiperazine. Other examples of polyamines that can be used in the current invention include, but are not limited to, ethylenediamine, dimethyl ethylenediamine, piperazine, pyrazolidine, imidazolidine, 2-(2-pyrrolidyl)pyrrolidine, 2-(2-imidazolidyl)imidazolidine, 3-(3-pyrrolidyl)piperidine, 2-(3-pyrrolidyl)piperazine, 3-(3-piperidyl)piperidine, 3-(2-piperazinyl)piperidine, and 2-(2-piperazinyl)piperazine.
It is preferred, though not required, that the amines of the current invention are not sterically hindered. One advantage of the current invention is a potentially high rate of reaction of CO2 with the solvent. If one or more of the amine function on the polyamine are sterically hindered by substituent groups, the rate of CO2 reaction and absorption may be significantly reduced.
A mixture of two or more polyamines may be used in place of a single polyamine compound in the solvent. For example, piperazine may be combined with aminoethylpiperazine or another polyamine in a ratio of 1/20, 1/10, 1/5, 3/10, 2/5, 1/1, 3/5, 7/10, 4/5, 9/10, 10/9, 5/4, 10/7, 5/3, 5/2, 5/1, 10/1, 20/1 or any ratio therebetween. If a mixture of polyamines is used, the preferred concentration ratio of salt to polyamine is based on the total concentration of the amine groups.
The polyamines described herein can be purchased from a variety of commercial sources as is known in the art or synthesized through standard chemical techniques known in the art. piperazine can be obtained, for example, by reacting monoethanolamine with ammonia, or by reacting ethylene oxide and NH3 and then cyclizing the ethanolamine byproduct.
Embodiments of the current invention provide using at least 3.0 equivalents/Kg H2O for the polyamine and at least 0.5 equivalents/Kg H2O for the alkali salt. In a preferred embodiment, the solvent will have either a substantially equal blend of the two components or a blend having up to a 2-to-1 ratio of the alkali salt to the polyamine. In a more preferred embodiment, the solvent will have a substantially equal blend of the two components at a concentration of at least 3.0 equivalents/Kg H2O. This can be distinguished from other systems that use "promoters," which are smaller, catalytic amounts of amines, designed to improve absorption characteristics in a concentrated solution containing a less reactive amine or potassium carbonate. Examples of promoter technology is provided in U.S. Pat. No. 4,336,233 to BASF, which proposes 0.05 to 0.8-M aqueous PZ or more preferably 0.05 to 0.4 M PZ as a promoter in a solvent containing MDEA.
The amount of alkali salt and polyamine in the solution is limited by the solubility of both components. Both pure potassium carbonate and pure piperazine are solids, resulting in solid solubility limits for aqueous solutions. At 25° C. the solubility of potassium in a CO2 rich solution is 3.6 m and the solubility of PZ in water is approximately 2 m. With a solid solubility limitation, the resulting lower concentrations can result in slow reaction rates and low solution capacity making the solvent unattractive. By combining PZ and potassium carbonate in an aqueous solution the solid solubility is increased to as much as 3.6 m PZ, allowing a greater total concentration of solute and potentially increasing the absorption rate and capacity. At higher temperatures, the solubility increases even more and allows for more concentrated solutions to be used. It has been suggested that PZ concentrations greater than 1.3 m can not be used in a CO2-rich environment (in the absence of an alkali salt) due to the formation of piperazine carbamate that precipitates from the solution. (U.S. Pat. No. 4,336,233). However, greater concentrations of alkali salts and polyamines are feasible without precipitation of solids. Greater reagent concentrations increase the capacity of the solvent and reduce remaining energy requirements associated with the sensible heat of the solvent. Greater polyamine concentration also enhance CO2 absorption rates.
The concentration of K2CO3 solvent without PZ is limited by the precipitation of KHCO3. Available data suggests that rich solution with a CO2 partial pressure of 0.1 atm will be limited to 30 wt % K2CO3 at 40° C. and 35 wt % at 60° C. (Bocard, J. P., and B. J. Mayland, "New Charts for Hot Carbonate Process," Hydroc. Proc. & Pet. Ref., 41(4), 128, 1962; Tosh, J. S. et al., "Equilibrium Study of the system potassium carbonate, potassium bicarbonate, carbon dioxide, and water," USBM RI 5484, 1959). It is understood that operation near the solubility limit may require careful process control.
Below 40° C., the stable PZ solid is PZ.6H2O, with a solubility of 1.8 M PZ at 25° C. Above 40° C., the stable phase is anhydrous PZ with a solubility of 7.4 M at 40° C. It is possible that high salt concentrations, such as K+CO3−/HCO3−, will reduce the solubility of the free PZ as much as a factor of 2. But less than 25% of the total PZ will be present as free PZ in the lean solvent. Therefore, even if the precipitation of PZ.6H2O below 40° C. limits the solvent composition, concentrations of up to 3 M PZ can be used. An aqueous solution that contains only PZ could be used as a scrubbing solvent, however, it would have limited applicability since, at concentrations above about 1.3 M, piperazine precipitates in the presence of CO2 as the carbamate. The solubility of piperazine in water at 20° C. is only 1.5 M. U.S. Pat. No. 4,336,233.
It is therefore advantageous to combine a polyamine and an alkali salt at relatively high concentrations. A polyamine will have a concentration of at least 1.5 m, or 3.0 equivalents for a diamine per Kg water, and the alkali salt will have a concentration of at least 0.5 m or 1.0 equivalents for a divalent salt per Kg water. In a preferred embodiment the ratio of the polyamine to the alkali will be approximately 1 to 1, for example 3.6 equivalents PZ/Kg water and 3.6 equivalents potassium/Kg water. Similarly, both components may have concentrations of 1.5 equivalents/Kg water ore both components may have concentrations of 5.0 equivalents/Kg water. This one-to-one ratio of alkali salt to amine moiety provides for effect solubility of both components and solvation of CO2. Other 1:1 ratios of alkali salt to amine moiety include but are not limited to 2:2, 2.5:2.5, 3:3, 3.5:3.5, 4:4, 4.5:4.5, 5.5:5.5, 6:6, 6.5:6.5, 7:7, 7.5:7.5, 8:8, 8.5:8.5, 9:9 equivalents/Kg water. Other concentration ratios may also be used; for example, an excess of salt for a solvent having 3.0 equivalents/Kg water potassium carbonate and 1.5 equivalents/Kg water PZ may be used. Concentration ratios contemplated in the current invention include but are not limited to salt/amine equivalents ratios of approximately: 3:1, 2.9:1, 2.8:1, 2.7:1, 2.6:1, 2.5:1, 2.4:1, 2.3:1, 2.2:1, 2.1:1, 2:1, 1.9:1, 1.5:1, 1.7:1, 1.6:1, 1.5:1, 1.4:1, 1.3:1, 1.2:1, 1.1:1, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.5, 1:1.9, 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9, and 1:3. Other ranges considered include 4:1, 3.9:1, 3.8:1, 3.7:1, 3.6:1, 3.5:1, 3.4:1, 3.3:1, 3.2:1, 3.1:1, 1:3.1, 1:3.2, 1:3.3; 1:3.4; 1:3.5; 1:3.6, 1:3.7, 1:3.8, 1:3.9, and 1:4.
In the absence of a polyamine, CO2 reacts with carbonate to give bicarbonate. The heat of this reaction is about 5 kcal/gmol:CO2(g)+CO3=+H2O→2HCO3−
By combining a polyamine such as piperazine and carbon dioxide, the piperazine undergoes equilibrium reactions as shown in the following reactions.PZ+CO2+H2OPZCOO−+H3O+PZCOO−+CO2+H2OPZ(COO−)2+H3O+In this reaction, PZ (C4N2H10), reacts with CO2 to make PZ-carbamate (PZCOO−) and PZ-dicarbamate (PZ(COO−)2). In the limit of reaction, the stoichiometry would be:CO32−+2·PZCOO−+CO22·PZ(COO−)2
Free piperazine is not shown to be present to contribute to volatility in this reaction. However, free piperazine will be present in the solution, but is in lesser amounts as CO2 or CO32— is added to the solution. The addition of potassium carbonate would both add CO32− to the solution and provide a dissociated cation to combine with anionic piperazine species.
Carbonate will buffer to give the overall reactions:CO2(g)+CO32−+PZ→PZCOO−+HCO3−CO2(g)++CO32−+PZ-COO−→PZ(COO−)2+HCO3−
In solutions with large concentrations of PZ where these reactions dominate, the heat of absorption of CO2 will be as much as 20 kcal/gmol. Therefore the expected heat of absorption in solvents containing both the alkali salt K2CO3 and the polyamine PZ will vary from about 10 to 20 kcal/gmol, depending on the concentration of PZ. An advantage of the solvent system containing a polyamine and an alkali salt is the ability to tune the heat of absorption by changing the salt/polyamine ratio. For comparison, the heat of absorption of CO2 in MEA solvents is about 22 kcal/gmol.
Although the reactions above are specific for PZ, other polyamines will react similarly, with each amine group reacting with CO2 to make carbamate, dicarbamate, tricarbamate, etc.
The effect of the innovative solvent on CO2 absorption rates at 60° C. is shown in FIG. 1. Solvents with K+/PZ ratios of one to two give absorption rates that are 1.5 to 5 times faster than other common solvents (5.0 M MEA) and other solvents promoted with less piperazine.
While the piperazine reaction mechanism is typical of other amines, the presence of potassium carbonate in the solution significantly enhances the reaction rates as is shown by the value of the specific rate constants in Table 1. The rate expression for the calculations in Table 1 is given by:r=(kPZ-OH[PZ][OH−]+kPZ[PZ]+kPZCOO−[PZCOO−])[CO2].Also evident is apparent accelerated rate behavior in the presence of a base such as hydroxide or carbonate. Both characteristics are advantageous because faster absorption rates will result in less energy requirements and/or capital cost can be reduced. The rate of absorption could be increased by a factor of three over other amine solvents.
TABLE 1Specific Rate Constants for the Piperazine-CO2Reaction With and Without Potassium PresentkPZ-OHkPZkPZCOO−(m6/mol2-s)(m3/mol-s)(m3/mol-s)Without K+0.05447With K+2.629047*kMEA = 7 m3/mol-s
Because of the increased rates of absorption in the current invention compared to methods known in the art, several cost optimization options are available for use with the present invention. First, the faster rates allow operating at a closer approach to equilibrium. This has the potential to reduce energy requirements by a factor of three. Second, the tower height can be reduced, lowering the required amount of packing in a column. This also reduces the pressure drop through the column and, consequently, reduces energy costs. Finally, some optimum combination of the previous two cases may be considered to reduce both capital and operating costs.
Even with the formation of ionic species in the solvent, there will still be some free piperazine. The volatility will be a concern if not addressed. This problem can be reduced or eliminated by the use of a water wash system. Most amine processes already contain water wash trays to collect amines from treated gas in the absorber and stripper.
The degradation of piperazine in solution is also believed to be significant. It is expected that carbamate polymerization, one mechanism for degradation, will occur at slower rates than in MEA and other amine solvents. The potential of oxidative degradation is also present and may or may not be slower than MEA.
The current art for CO2 capture from flue gas is absorption/stripping with 15 to 30 wt % aqueous MEA. 90 to 99% of the CO2 is removed in an absorber with 40 to 60 feet of dumped packing at atmospheric pressure. The pressure drop and capital cost of the absorber are large and could be significantly reduced by the enhanced CO2 absorption rate. The temperature for the absorption process should be between 25° C. and 120° C., or more preferentially between 40° C. and 80° C.
Absorption/stripping processes known in the art, such as those provided by Exxon and UOP, provide technologies with isothermal absorption/stripping at 90 to 120° C. The stripper typically operates slightly above atmospheric pressure. These systems utilize isothermal, pressure swing regeneration rather than thermal swing because the heat of desorption of CO2 (5 kcal/mol) is less than the heat of vaporization of water (10 kcal/mol). Greater temperature in the stripper does not increase the volatility of CO2 relative to that of water. The solvent in these systems is regenerated in a stripper with 40 to 60 feet of packing near atmospheric pressure at 110 to 130° C. The demand for moderate level heat (30-60 psi steam) to drive the reboiler is large, approaching 20 to 30% of the thermal requirement for the power plant.
Generally, the CO2 removal process consists of an absorber column in which a CO2-rich gas stream contacts a circulated chemical solvent between approximately 40 and 100° C. The solvent, after absorbing CO2, is passed to a stripper column where the CO2 in solution is removed by heating to approximately 50 to 150° C., or more preferentially between 60° C. and 130° C., and most preferentially between 100° C. and 130° C. The solvent is then returned to the absorber as a CO2-lean solution.
The combination of potassium carbonate and piperazine as a solvent for this process yields flexibility and advantages over current state-of-the-art solvents. K+/PZ blends are effective for getting good rates of CO2 absorption; the rates can be two to three times faster than 5.0 M MEA. The blend also improves solid solubility of both components and may reduce the volatility of piperazine.
Various methods of stripping may be used, including stripping with vapor recompression, stripping with turbine exhaust steam, and multi-stage stripping. In one embodiment, CO2 capture from flue gas using the solvent of this invention uses isothermal operation with a vacuum stripper. The low pressure of the absorber (1 atm) will not permit operation at temperature greater than 50 or 60° C. without requiring additional heat to evaporate large quantities of water. The solvent will effectively catalyze the absorption and desorption of CO2 at this lower temperature.
The absorption and stripping can be carried out at atmospheric or superatmospheric pressures. The stripper pressure can be adjusted to minimize the energy requirement of the system, and can be determined through modeling. This modeling will also optimize the amount of packing in the absorber and stripper. As the temperature and pressure of the stripper are reduced, the rate of reaction to produce CO2 will also decrease and the mass transfer capability of the stripper will be reduced.
The process may also involve a one-step or a two-step washing step to collect the polyamine. The wash may be a water wash and can occur at the absorber column or at the stripper column.
CO2 absorption and desorption in the alkali salt and polyamine solvents is determined primarily by diffusion of CO2 in the liquid film with fast reaction near the gas liquid interface. The rate is mostly independent of the gas and liquid film mass transfer coefficients and depends on the gas liquid contact area. The flux depends on the square root of kinetics of the reaction, in this case, with the species PZ and PZCOO−.
The rate constants kPZ and kPZCOO− have been determined from measurements in water and in 50% MDEA. These values are 5 to 10 times faster than the comparable rate constant for MEA. Doubling the concentration of PZ species increases the rates of CO2 absorption by approximately 40%. The effective gas film mass transfer coefficient is a strong function of loading and decreases a factor of 4 from lean (0.003 atm) to rich (0.06 atm) conditions.
With low CO2 concentration and high free amine concentration, the rate of CO2 absorption will be controlled solely by the gas/liquid contact area. At greater CO2 concentration and reduced free amine concentration, the CO2 absorption will be controlled to a greater extent by liquid film diffusion of the polyamine.
Additional measurements of CO2 absorption/desorption can be made in a wetted wall column with the alkali salt and polyamine solvents over a wider range of conditions. The apparatus is described by Mshewa, M. M. "CO2 Desorption/Absorption with Aqueous Mixtures of MDEA and DEA at 40 to 120° C.," Ph.D. Dissertation, 1995; Pacheco, M. and G. T. Rochelle, "Rate-based Modeling of Reactive Absorption of CO2 and H2S into Aqueous Methyldiethanolamine," Ind. Eng. Chem. Res., 37(10), 4107-4117, 1998; Pacheco, M., "Mass Transfer, Kinetics and Rate-based Modeling of Reactive Absorption," Ph.D. Dissertation, May 1998; Pacheco, M., S. Kaganoi, and G. T. Rochelle, "CO2 Absorption into Aqueous Mixtures of Diglycolamine and Methyldiethanolamine," Submitted to Chem. Eng. Sci., Jul. 5, 1999; Bishnoi, S, and G. T. Rochelle, "Absorption of Carbon Dioxide into Aqueous piperazine: Reaction Kinetics, Mass Transfer and Solubility," presented at the 49th Annual CSChE Conference, Saskatoon, Saskatchewan, Oct. 3-6, 1999; and Bishnoi, Sanjay. "Carbon Dioxide Absorption and Solution Equilibrium in piperazine Activated Methyldiethanolamine." Doctor of Philosophy Dissertation, The University of Texas at Austin, 2000. This system has been used for measurements of PZ/MDEA (Bishnoi, Sanjay. "Carbon Dioxide Absorption and Solution Equilibrium in piperazine Activated Methyldiethanolamine." Doctor of Philosophy Dissertation, The University of Texas at Austin, 2000) and PZ/MEA (Dang, Hongyi. "CO2 Absorption Rate and Solubility in Monoethanolamine/piperazine/Water." Master of Science Thesis, The University of Texas at Austin, 2001). The wetted wall column was constructed from a stainless steel tube with a well defined surface area (38.5 cm2) and a characteristic liquid film mass transfer coefficient similar to that of a packed tower. Rate of absorption is determined from the gas phase material balance using the measured inlet and outlet gas concentration. Solubility is measured by bracketing equilibrium with both absorption and desorption measurements. The operating conditions can be varied from 25 to 120° C., 1 to 7 atm total pressure, and 0001 to 1 mole fraction CO2.
The polyamine in the solvent will undergo some amount of oxidative degradation. For PZ, this process causes the formation of ethylenediamine, formate, glycolate, and other amine and organic acid fragments. To reduce the amount of oxidative degradation of the solvent, antioxidants may be added to the solvent system or a vacuum stripper may be used. Any antioxidant known in the art may be used in the current invention. Typical concentrations for antioxidants range from about 0.01 to 5% by weight.
Other additional agents may also be added to the solvent of the current invention. These agent may act, for example, as an antifoaming agent, a flocculation aid, or a corrosion inhibitor. Typical concentrations for these additives range from about 0.01 to 5% by weight. These agents are well known in the art and may include, for example, vanadium oxides (e.g. V2O3), chromates (e.g. K2Cr2O7), arsenious anhydrides, selenious acid, tellurous acid, protides, and amino acids.
The volatility of the polyamine PZ in the solvent of the current invention is low because less than 20% of it will be free PZ in lean solution. This increases the safety of the solvent. Any environmental impact could be minimized by using a water wash in the top of the absorber.
Various methods for describing solution concentrations are used herein, including molarity (moles solute/liter solution, M), molality (moles solute/Kg solvent, m) weight percent, and equivalents/Kg H2O. At low solution concentrations, molarity and molality will be substantially the same as will the equivalents/Kg H2O when the component has a single equivalent of the reactive component (e.g., a monoamine). 1.5 m K2CO3 is approximately 20 wt % K2CO3. For example, 1.8 m K2CO3 has 3.6 equivalents K+/Kg H2O and 1.8 m of the trifunctional amine, diethylenetriamine has 5.4 equivalents amine/Kg H2O.

Polyamine/alkali salt blends for carbon dioxide removal from gas streams

The Board of Regents of the University of Texas System


A method for writing data into a reprogrammable non-volatile memory, wherein a marking pattern including several bits is added at the beginning of the data and the set formed of the marking pattern and of the data is written from an address in the memory varying from one write operation to another, the marking pattern being identical for each write operation.

Field of the Invention
The present invention relates to the field of microcontrollers embedded in electronic elements and to the implementation of atomic transactions in such devices. More specifically, the present invention relates to a method for writing into or reading from an atomicity memory.
Discussion of the Related Art
In embedded microcontrollers, for example, contact or contactless chip cards, the atomicity of transactions is essential. A transaction is said to be atomic if, when it is under way and an interrupt occurs, for example, due to an interruption of the device power supply, the data stored in a non-volatile memory are, after the device has been reactivated, either in the state prior to the transaction, or in the final state after the transaction. If the state of several sets of memory cells has to be changed during a transaction, all the memory cells should be updated or reset to their state prior to the transaction. For an atomic transaction, an intermediary or undetermined state of areas storing the data of this transaction in the non-volatile memory must not be allowed.
Many techniques are known to determine whether a transaction has occurred properly and whether the state of the non-volatile memories to which it has been accessed has been updated properly. To perform atomic transactions, it is current to use a memory area of the non-volatile memory, which is called "atomicity memory (or buffer)", to store, before each transaction, the state of the non-volatile memories capable of being modified during the transaction. This enables, in the case where the transaction would be interrupted, to restore in non-volatile memories all the data preceding the transaction by reinjecting the data stored in the atomicity buffer. It is also known to store, in an atomicity buffer and before each transaction, the new data intended to be stored in the non-volatile memories at the end of the transaction. If the transaction is interrupted, the data stored in the atomicity buffer enable to complete the transaction.
In the case where the transaction has succeeded, the data contained in the atomicity buffer are erased. Generally, atomicity buffers are formed of electrically erasable and programmable non-volatile memories, better known as EEPROMs.
A problem of the use of EEPROMs is that such memories are unable to withstand a number of write operations greater than 500,000 cycles and tend to degrade along write and erase operations. Further, the degradation of the buffer memories is not uniform since the number of data to be written into the atomicity buffer varies according to the performed transactions. Thus, the first memory areas (first memory addresses) of the atomicity buffer are reached for each transaction while the last memory areas are only used in transactions modifying the state of a large number of memory cells.
Thus, a buffer formed of EEPROMs non-uniformly degrades along write and read operations.

Method for writing into and reading from an atomicity memory using marking pattern


A control device is provided for electrically controlling a drive power transmission device arranged on a driving power transmission path of a front-and rear wheel drive vehicle thereby to switch the drive mode of the vehicle selectively to either of a two-wheel drive mode and a four-wheel drive mode. The control device inhibits the drive mode from being switched to that commanded to be switched to when the vehicle is traveling at a slower speed than a predetermined speed and when the rotational speed difference between front and rear wheels is larger than a predetermined value. Further, the control device gradually decreases a present torque which the driving power transmission device is transmitting before the switching of the drive mode, to a target torque which the drive power transmission device is to transmit after the switching of the drive mode, when the difference between the present and target torques is more than another predetermined valve at the time of the switching of the drive mode. Thus, the driving power transmission path can be prevented from generating the drive torque beyond a tolerable valve as well as making a noise due to the instantaneous switching of the drive mode during the traveling of the vehicle, and the vehicle can be prevented from abruptly changing its motion by the cause of the instantaneous drive mode switching.

1. Field of the Invention
The present invention relates to a control device for controllably switching the drive mode of a front-and-rear wheel drive vehicle to a drive mode commanded to be switched to by electrically controlling a drive power transmission device installed on the front-and-rear wheel drive vehicle.
2. Discussion of the Related Art
Heretofore, as described in Japanese unexamined, published patent application No. 2001-82571, there have been known a front-and-rear wheel drive vehicle of the type having a driving power transmission device on a driving power transmission path for transmitting the driving power from a driving power source to driven wheels such as, for example, rear wheels. The driving power transmission device installed on the front-and-rear wheel drive vehicle is provided in the driving power transmission path extending from the primary driven wheels to the secondary driven wheels and operates to transmit the driving power to the secondary driven wheels. The driving power transmission device may otherwise be installed inside of a center differential which distributes the driving power to both pairs of driven wheels and operates as a limited slip differential.
The aforementioned front-and-rear wheel drive vehicle is provided with a control device for electrically controlling the driving power transmission device. The control device is capable of selectively switching the drive mode of the vehicle to either of various driving modes by electrically controlling the driving power transmission device. With such a control device, the drive mode of the vehicle can be controllably switched to, for example, two-wheel drive mode, automatic four-wheel drive mode, four-wheel drive lock mode, or the like.
However, the aforementioned control device in the prior art takes the construction that when a driver or the like applies a switching command signal to the control device to switch the drive mode from the present one to a desired one, the switching to the commanded drive mode is effected instantaneously regardless of the state of the vehicle at that moment. Thus, it may be the case that in dependence on the state of the vehicle at the time of such a switching command given, an excessive driving force (i.e., torque) may be transmitted instantaneously to the driven wheels. This undesirably results in the occurrence of a torque exceeding an allowable level, the generation of an abnormal sound or noise, the abrupt change in the vehicle motion or the like.
For example, while the vehicle traveling at a low speed in the two-wheel drive mode is suffering a large slip, the switching to the four-wheel drive mode may cause the torque to be transmitted to the secondary driven wheels abruptly. This may make a cause to the generation of a torque exceeding the allowable level or an abnormal sound. Furthermore, when the torque is changed abruptly by the instantaneous switching of the drive mode during the vehicle traveling, the motion of the vehicle suddenly changes, especially where the vehicle is making a turn.

Control device for front-and-rear wheel drive vehicle


On each side of a drawer is a pull-out rail secured to the drawer and a support rail secured to a furniture body. Load-transmitting rollers are mounted between the rails. Provided on one side of the drawer is a closing device including a guide housing mounted on the body and having a guide groove to guide a plate-shaped tilt segment which is acted upon by a spring. The tilt segment is displaceable along the guide grooves by guide pegs extending into the guide groove. An entrainer peg on the drawer couples to the tilt segment. The guide groove is arranged in the guide housing on a side thereof facing the support rail. The tilt segment projects laterally from the guide housing and has two laterally projecting stabilizing pegs which, in end positions of the tilt segment, fit on and abut support surfaces of the guide housing on a side thereof remote from the guide groove.

The invention relates to a closing device for a drawer, there being provided on each side of the drawer a pull-out rail secured to the drawer and a support rail secured to a furniture carcass or body, and load-transmitting rollers or the like bearing on or between the rails. A closing device is provided on at least one side of the drawer and includes a guide housing, preferably mounted on the body, and which has a guide groove for a plate-shaped tilt segment or tiltable member which is acted upon by a spring and which is displaceable along the guide groove means of guide pegs extending into the guide groove. When the tiltable member is displaced in a pull-out direction of the drawer, it is coupled to an entrainer peg or pin member, which is preferably on the drawer. The tilt segment is acted on by a restoring-ensuring means, i.e. the spring, and is arranged in the guide housing on a side thereof facing a mounting surface therefor, for example the support rail, and is guided therein in concealed manner but projects laterally therefrom.
Modern drawers are provided with a pull-out guide fitting which on both sides of the drawer comprises a body or carcass-side support rail and a drawer-side pull-out rail and is intended to make the displacement movement of the drawer as smooth as possible. For transmission of load between the drawer-side pull-out rails and the carcass-side support rails, rollers, balls or indeed slides can be provided, depending on the requirements of the drawer regarding quiet running and load.
It has been found that in some cases a closed drawer does not retract completely into the rear end position, that is to say into the body, and a front panel of the drawer projects forwardly of the furniture body. This can result in bumping against the drawer, which in turn can result in personal injury or damage to the drawer.
The fact that the front panel of the drawer protrudes from the furniture front can be the consequence of the drawer having been pushed in carelessly and not fully into the furniture body. However, if the drawer is pushed into the furniture body with too much force, as well, the drawer can roll forwardly again as a result of such excess energy.
British Patent Specification 1 117 071 discloses a device for keeping a drawer closed, in which a tilt part movable between two end positions is provided. The tilt part is acted upon by a helical spring and is urged thereby into a respective end position after overcoming a dead center position. The tilt part is secured to a side wall of the furniture body. The drawer has on the side wall an entrainer peg which is retracted in the end region of the travel of the drawer into a notch in the tilt part. Then, the entrainer peg presses the tilt part beyond the dead center position, whereupon the tilt part itself disengages from the entrainer peg and thus pulls the drawer backwards.
EP-A1-0 391 221 discloses a closing device for a drawer, in which a tilt segment, which is acted upon by a tension spring, is moved linearly in a guide groove in a pull-out direction in order then to tilt into a front locking position. Thus, the drawer is entrained a further distance by the closing device.


There is provided a method and apparatus for measuring the optical properties of bulk samples. A probe laser beam is fed into the two arms of the apparatus, a reference arm and a measurement arm, both of which contain optical fiber to conduct the laser lights. The measurement arm includes a free space area for mounting a sample to be tested. The probe beam is directed into the sample in free space. The sample also receives light in free space, rather than via the optical fiber, from a second, pump laser. The interaction of the sample and the pump laser affect the optical properties of the sample. This change in optical properties can be detected by comparing the output signals from the measurement and reference arms.

The role of nonlinear materials in high-speed applications such as optical switching, amplification, limiting and frequency conversion has created a need for an efficient method of characterizing nonlinear parameters. Many of these parameters can be characterized by the analysis of the index of refraction of a material. In particular, semiconductor materials exhibit a broad range of nonlinear effects with response times that span several orders of magnitude, owing to electronic nonlinearities, free-carrier effects, and thermal nonlinearities. Other materials may also exhibit properties which change over time, e.g., due to optical interaction or to environmental factors, and which also change the materials' index of refraction.
The presence of two or more nonlinear mechanisms can complicate the interpretation of optical nonlinearities because many techniques cannot distinguish between them. Quantitative information concerning the nonlinear index of refraction for optical materials is essential for the development of all-optical devices, such as opto-optical switches. Several techniques have been proposed for conducting this measurement, most of which are based on a direct interferometric measurement that uses a pump and probe technique.
One technique is to analyze temporal interference fringes to obtain the nonlinear index of refraction, as described in "Nonlinear-Index-Of-Refraction Measurement In A Resonant Region By The Use Of A Fiber Mach-Zehnder Interferometer", Applied Optics, Vol. 35, No. 9, Mar. 20, 1996, pages 1485-88. This technique uses fiber light guides in both the reference and measurement arms. Also included in each arm is an adjustable delay unit (AD) based on an optical fiber pigtailed graded index rod-lens pair, to vary the optical length of each arm.
The inventors have found that this technique is difficult to use to do measurements of bulk sample properties because of the difficulty in preparing an interface between the light guides in the measurement path and the sample to be measured. Often, it is possible that installing connecting light guides to the sample will result in some shift of its electrical properties. In addition, some samples cannot be connected directly to optical light guides.
Furthermore, according to this technique the pump pulses propagate in the optical fibers comprised in the interferometer arms; the inventors have observed that this sets a limit to the maximum pump power available for the measurements.
Another technique is disclosed in "Time-Resolved Absolute Interferometric Measurement Of Third-Order Nonlinear-Optical Susceptibilities", Journal of the Optical Society of America B, Vol. 11, No. 6, June 1994, pages 995-999. This technique, as illustrated in FIG. 1 of the paper, uses free space propagation of optical signals to measure nonlinear optical properties of bulk materials. A Mach-Zehnder interferometer compares the two beams (probe and reference) in amplitude and phase. The sample is located in the probe arm and interacts with the stronger collinear pump beam. The time delay .tau. between the pump and probe pulses provides the basis for a sampling interferometry.
The inventors have observed that the above techniques has disadvantages linked with using an optical measurement system wherein the light propagates completely in free space; in particular it is bulky and it needs careful alignment of all the optical components, what renders this technique difficult to use.
Other discussions of measurement of nonlinear properties can be found in "Femtosecond Time-Resolved Interferometry For The Determination Of Complex Nonlinear Susceptibility", Optics Letters, Vol. 16, No. 21, Nov. 1, 1991, pages 1683-1685 and "Interferometric Measurement Of The Nonlinear Index Of Refraction n.sub.2 Of CdS.sub.x Se.sub.1-x -Doped Glasses", Applied Physics Letters, Vol. 48, No. 18, May 5, 1986, pages 1184-1186.
U.S. Pat. No. 5,268,739 discloses a laser apparatus for measuring the velocity of a fluid. In the system disclosed, a laser beam is fed into a pipe through which a fluid is flowing. Particles in the fluid interfere with the light. The velocity of the fluid is calculated from this interference.

Interferometer for measurements of optical properties in bulk samples


An internal combustion engine comprises a primary supercharger operated in substantially a full range of engine operating conditions of a vehicle and a secondary supercharger operated in a specific range of the engine operating condition. The plurality of supercharger are arranged in parallel in the fore and aft direction of a vehicle in a manner such that the primary supercharger means is disposed forward of the secondary supercharger. The primary supercharger is disposed at a front portion of an engine room, just behind a cooling fan, to easily be provided with a cooling effect by virtue of a fresh air. The secondary supercharger is disposed rearward of the primary supercharger to avoid the cooling effect provided by the fresh air and to receive air warmed by the primary supercharger so to undergo a warming up effect.

1. Field of the Invention
This invention relates to an internal combustion engine with a turbo supercharger provided with a turbine driven by exhaust gas, and a compressor connected with the turbine by a common shaft. The compressor is driven by the turbine for compressing intake air to provide a supercharging effect on the intake gas, more specifically to an engine with a primary turbo supercharger operated mainly and a secondary turbo supercharger operated in a specific engine operating condition.
2. Description of the Prior Art
Conventionally, there has been known an internal combustion engine with a primary and secondary turbo superchargers wherein a control for the superchargers is switched between a first condition, in which one of them is driven, and a second condition, in which both of them are driven, in accordance with an engine operating condition, as disclosed in Japanese Utility Model Public Disclosure No. 60-178329. Japanese Patent Public disclosure Nos. 56-41417, 59-160022, 60-259722 (corresponding to European patent application No. 166869) and Japanese Utility Model Publication No. 57-12177 disclose similar types of engines, respectively. The engine disclosed in Japanese Utility Model Disclosure No. 60-178329 is provided with a plurality of cylinders having respective exhaust passages therefrom. The exhaust passages are divided into two groups. There are provided gate valves for controlling introduction of the exhaust gas into the turbo superchargers. Under the first condition, the exhaust gas from the cylinders are introduced into only the primary turbo supercharger through one of the groups of the exhaust passages by virtue of the operation of the gate valves. In the second condition, the exhaust gas is introduced into both the primary and secondary turbo superchargers. Such engines as disclosed in the Japanese publication can improve the efficiency of supercharging effect in accordance with the engine operating condition.
Meanwhile, in order to get a better performance of the turbo supercharger, it is critical that the superchargers are kept in an appropriate thermal range.
It should, however, be noted that it is difficult for the conventional internal combustion engine with a plurality of turbo superchargers to provide all of the turbo superchargers with a substantially uniform, thus proper, thermal condition while operating. This is because an operating conditions is different in each supercharger, for instance, the primary turbo supercharger which is driven in any supercharging condition of the engine, tends to be heated because of a heavy load in operating period, as compared with the secondary turbo supercharger, which is driven in only a specific engine operating condition. The turbo superchargers are usually arranged to be subjected to an air cooling effect by a cooling fan and blowing air into an engine room while the vehicle is running, in addition to a cooling effect provided by a coolant. As a result, some of the turbo superchargers are kept at an unduly high temperature and some of them at an unduly low temperature. This may cause a deterioration the warming up property of the superchargers.

Internal combustion engine with turbo supercharger


Methods and apparatus involve evaluating endpoint computing assets. The endpoint has both a traditional operating system for applications, and the like, and another operating system during a pre-boot phase of operation. During use, the traditional operating system identifies a last evaluation status of the computing device at a time just prior to shutting down. Upon a next booting, the pre-boot operating system loads and examines [reads] the last evaluation status. If the last evaluation status requires any completion action in order to comply with a predetermined computing policy, either or both the operating systems attend to its effectuation, including communication/handoff by way of one or more security agents. In a variety of ways, effectuation occurs by: determining a present location of the computing device, quarantining the computing device from certain network traffic; VPN enforcement; patching applications; firewall involvement; etc. Computer program products are also disclosed.

Today, corporate computing assets, such as laptops, phones, PDAs, etc., are utilized outside corporate firewalls more than ever before. With ever more employees either working from home or "on the road," controlling and managing corporate information technology (IT) assets is becoming a difficult or serious problem. For instance, troubleshooting and repairing remote endpoints requiring manual, "hands on," intervention are extremely costly to companies or IT departments. While a few technologies have emerged that facilitate diagnosis, and occasional remediation, the means of accomplishing this are not secure. As such, they risk security not only to the hardware and data files of the endpoint device, but also to the entire corporate enterprise as infected devices are brought behind and used inside the corporate firewall.
More particularly, some of the present technologies rely on either network communication (level 2 (MAC) or level 3 (IP)) to the endpoint, 802.1X authentication and information exchange, or some type of "pre-boot" Operating System. While minimally useful, the former is problematic for lack of having an IP stack up and functioning, while the latter only typically diagnoses hardware items, such as a bad drive, without any attendant capability to diagnose more rigorous or esoteric items such as non-complying computing policies, encryption functionality, VPN enforcement, or the like. Neither can certainly do it as a function of a particular location of the endpoint computing asset as the asset moves from location to location in a mobile environment. With the advent of virtual computing devices, such problems are only exacerbated since a single hardware platform will often guest many virtual computing devices, each with its own operating system (potentially vastly different from one another), drivers, interfaces, applications, etc.
Accordingly, a need exists in the art of evaluating endpoint computing assets for better diagnosis, especially for rigorous and esoteric matters. Also, such needs to occur securely. Even more, the need extends to virtual environments, each with many domains per a single hardware platform, and to mobile environments as assets move about during use. Naturally, any improvements should further contemplate good engineering practices, such as ease of implementation, unobtrusiveness, stability, etc.

Pre-boot securing of operating system (OS) for endpoint evaluation


An on-chip phase-locked loop circuit has reduced power consumption in a semiconductor integrated circuit. The phase locked loop circuit is equipped with a phase frequency comparator, a loop attenuator, a charge pump, a loop filter, a voltage controlled oscillator and a divider. The attenuator includes a sampling circuit and a counter. A sampling pulse and first and second output signals both outputted from the phase frequency comparator are supplied to the sampling circuit. The sampling circuit outputs a sampling output signal. When the counter completes a countup of a predetermined number of sampling pulses outputted from the sampling circuit, the counter outputs a countup completion output signal. The charge pump outputs a charging current or a discharging current to the loop filter in response to the countup completion output signal.

The present invention relates to a semiconductor integrated circuit having a phase locked loop (PLL) circuit built therein and an operating method thereof, and particularly to a technology useful in, when a loop filter is on-chipped in particular, reducing variations in the characteristics of the PLL circuit due to variations in the device size of each transistor and reducing increases in both circuit scale and power consumption of the semiconductor integrated circuit.
A phase locked loop (PLL) circuit has heretofore been mounted in a semiconductor integrated circuit. This PLL circuit generates a clock signal for operating a logic circuit such as a large-scale logic integrated circuit or the like.
The following patent documents 1 and 2 respectively have described that in order to on-chip a loop filter of a PLL circuit, a main charge pump circuit and a subsidiary charge pump circuit are coupled between a phase output terminal of a phase comparator and an input terminal of the loop filter. In the PLL circuit described in the following patent document 1, the main charge pump circuit and the subsidiary charge pump carry out charging and discharging operations based on outputs being in-phase to each other in response to a phase output signal of the phase comparator. The output of the subsidiary charge pump circuit is coupled to the input of a voltage-current converter of the loop filter. On the other hand, the output of the main charge pump circuit is coupled to the output of the voltage-current converter of the loop filter. In the PLL described in the following patent document 2, a main charge pump circuit and a subsidiary charge pump circuit perform charging and discharging operations based on outputs being in antiphase to each other in response to a phase output signal of the phase comparator. The output of the main charge pump circuit is coupled to one end of a resistor of the loop filter. On the other hand, the output of the subsidiary charge pump circuit is coupled to the other end of the resistor of the loop filter, and a filter capacitor is coupled between the other end of the resistor and a ground potential.
The following patent document 3 has described that in order to reduce the area of a charge pump PLL circuit, one component of an integrated voltage of a loop filter voltage is subtracted from the total loop filter voltage using a current mirror circuit.
The following patent document 4 has described that in order to bring a loop filter of a phase lock oscillator circuit into highly integrated circuitry for the purpose of its miniaturization, a digital circuit comprised of a counter, a decoder and an updown counter converts a pulse width of a charge signal or a discharge signal outputted from a phase detection circuit into a digital signal, and a D/A convertor converts the digital signal into an analog signal and supplies the analog signal to a voltage controlled oscillator in a manner similar to an analog voltage outputted from the loop filter.

Semiconductor integrated circuit having an on-chip PLL and operating method thereof


A multipolymer fiber comprising a polyester phase formed from at least one polyester resin, present at between about 50 to about 95 percent by weight and a polyamide phase formed from at least one polyamide resin, present at between about 5 to about 50 percent by weight, wherein the polyamide phase is distinct from the polyester phase and comprises a plurality of polyamide fibrils dispersed in the polyester phase, and wherein the polyamide fibrils are separately distinguishable from each other.

Polymers have long been the most prevalent material used for forming yarns for use in the carpet industry. In recent years, polyester has become a desirable polymer for use in carpet fiber.
Carpets made from polyester, particularly polyethylene terephthalate, are superior in terms of acid dye stain resistance, an important attribute, and they generally do well in terms of texture retention (durability) and soil resistance compared to the other low cost alternative, polyolefin (e.g. polypropylene). However, carpets made from polyester, particularly polyethylene terephthalate, perform quite poorly in terms of texture retention (durability) and soil resistance compared to polyamides, including nylon 66 and nylon 6, and wool. As a result, applications for polyester fibers in carpeting are often limited to those channels in which the poor durability and accelerated soiling attributes are minimized, for example in a low foot traffic residential environment. However, in high traffic environments, such as commercial office buildings, airports and schools, polyester fibers have not been considered durable enough for flooring installations. The negative aspects of polyester fiber performance in carpeting applications is, however, offset by the attractiveness of the price of polyester, which is typically favorable as a raw material due to the high supply volume of polyester raw materials.
There is, therefore, a need to improve the performance of polyester fibers for carpet applications that overcomes its durability and soiling deficiencies. The combination of polyamide and polyester resins has been contemplated to either reduce cost (of polyamide) or to improve the final carpet fiber properties (of polyester). However, the relative immiscibility of the polyester and polyamide resins chosen can create difficulty in forming conjugate fibers. Blends comprising immiscible polymers have two or more phases, and such blends may be incompatible. Incompatible blends of immiscible polymers can suffer from phase separation and fibers formed from such blends may fibrillate, which would not provide the durability necessary for commercial use. Additionally, polymers from the same class are frequently immiscible and form multiphasic compositions. Therefore, polymer miscibility is difficult to predict, even within the same class of polymers.
For this reason, previous attempts at using a combination of polyester and polyamides in carpet have required the use of a compatibilizing agent or an additional component. U.S. Pat. No. 6,780,941 to Studholme, herein incorporated by reference, teaches blending of thermoplastic polyester with fiber-forming polyamide in the production of melt-spun fibers, wherein the polyamide component forms the major phase. In order to form the fiber, the use of at least 1% by weight or more of a metal sulfonated poly(butylene terephthalate) as a compatibilizing additive is required.
PCT Publication No. 2013133640, herein incorporated by reference, teach that due to a lack of compatibility, it is difficult to melt extrude fibers from polyester and polyamides. To solve this problem, the addition of a compatibilizing agent, such as an epoxy resin is required to form a usable alloy fiber. In addition, this publication only teaches fibers with a polyamide major phase and an effective compatibilizer loading at 2% by weight or more.
U.S. Pat. No. 6,090,494 teaches fibers that contain both polyamide and polyester filaments. However, to be effective and avoid fibrillation, the amount of polyester is limited and only fibers containing predominantly polyamide filaments are disclosed.
European Patent Application No. 2,748,259A1 teaches a composition comprising both polyamide and polyester components, wherein the polyester component is preferred at 40% or less by weight, and without requiring a compatibilizer. However, the disclosure does not teach a composition that can be effectively melt spun into a fiber.

Multifilament fiber and method of making same


In general, according to one embodiment, a power amplifier includes an envelope detector, a limiter, and a combiner. The envelope detector is configured to sense an envelope component of an input signal. The limiter includes a PMOS (Positive channel Metal Oxide Semiconductor) transistor and an NMOS (Negative channel Metal Oxide Semiconductor) transistor. The PMOS transistor is configured to sense a phase component of the input signal. The phase component has a second-order distortion controlled within a predetermined range with respect to the input signal. The NMOS transistor is configured to sense a phase component of the input signal. The phase component has the same second-order distortion as the phase component sensed by the PMOS transistor. The combiner is configured to combine the envelope component sensed by the envelope detector and the phase component sensed by the limiter to generate an output signal.

An EER (Envelope Elimination and Reconstruction) system is adopted in an ordinary power amplifier that supplies an electric power to the radio communication device (see JP-A No. 2006-203456 (Kokai)). In the EER system, an envelope component of an input signal is processed by an envelope detector, and a phase component (hereinafter referred to as "input phase") of the input signal is processed by a limiter. The limiter shifts the input phase using an AM-PM (Amplitude Modulation-Phase Modulation) conversion method to generate a phase component (hereinafter referred to as "output phase") of an output signal.
However, in the EER system disclosed in JP-A No. 2006-203456 (Kokai), a degree of AM-PM conversion increases with increasing range (input amplitude range) of amplitude (hereinafter referred to as "input amplitude") of the input signal. Particularly, in an OFDM (Orthogonal Frequency Division Multiplexing) system, the degree of AM-PM conversion increases because of the wide input amplitude range (about 40 dB). Additionally, an allowable range of the degree of AM-PM conversion is comparatively narrow in the EER system disclosed in JP-A No. 2006-203456 (Kokai). Accordingly, the EER system disclosed in JP-A No. 2006-203456 (kokai) cannot be applied to the OFDM-system radio communication device having the wide input amplitude range.

Power amplifier and semiconductor integrated circuit


A machine-implemented method for automated detection of drowsiness, which includes receiving from an imaging device directed at the face of an operator a series of images of the face of the operator onto processing hardware, on the processor detecting facial landmarks of the operator from the series of images to determine the level of talking by the operator, the level of yawning of the operator, the PERCLOS of the operator, on the processor detecting the facial pose of the operator from the series of images to determine the level of gaze fixation by the operator, on the processor calculating the level of drowsiness of the operator by ensembling the level of talking by the operator, the level of yawning of the operator, the PERCLOS of the operator and the level of gaze fixation by the operator, and generating an alarm when the calculated level of drowsiness of the operator exceeds a predefined value.

According to the Australian Transport Council, drowsy driving causes between 20% and 30% of all deaths and injuries on the road [1]. Studies have shown that driving without sleep for 17 hours is comparable to driving with a blood alcohol concentration (BAC) of 0.05 (the legal limit of most countries including the USA, England and South Africa ranges between 0.05% and 0.08% [2]) and driving without sleep for 21 hours is comparable to a BAC of 0.15 (far over the legal limit) [1]. Drowsiness also affects many other industries where vigilance is required and can even be problematic for office workers.
In order to solve this problem, accurate drowsiness detection is needed. This would allow systems to be developed that alert operators when drowsiness is detected. Furthermore, it would allow companies and governments to monitor their operators and enforce vigilance.
Drowsiness detection has received an abundance of attention in recent years from both automotive companies and universities. A variety of approaches and methods have been researched and tested. These methods can be classified into three groups, namely, physiological methods, vehicle movement methods and computer vision methods.
Early methods made use of physiological measures such as respiration rate, heart rate and brain activity [3]. These methods are, however, intrusive as measurement devices must be attached to the operator. This can be dangerous if the measurement devices restrict the movement of the operator. Furthermore, the devices often hinder the comfort of operators and cause distractions, increasing the risk of an incident or accident.
Another method of drowsiness detection, geared towards drivers, is the monitoring of steering wheel movement [4] and vehicle movement. Sensors are typically placed inside the steering wheel or dashboard of a vehicle and measure the angular velocity and acceleration. This data is then used to classify erratic driving and swerving that is a characteristic of drowsy driving. A major drawback of this method is the large impact that road conditions and vehicle speed have on it. If road conditions are bad, drivers may swerve to avoid potholes and other obstacles which could be misinterpreted as drowsy driving. Additionally, the nature of the recorded data requires an extended period of analysis before an accurate classification of drowsiness can be made. This reduces the effectivity of the system as an accident may occur before classification. Placement of the sensors may also be problematic as they may interfere with the driver if they are not built into the vehicle.
Advances in computer vision have allowed drowsiness detection to be performed by observing facial features such as the eyes and mouth. Facial characteristics of drowsiness include a smaller degree of eyelid opening, slow eyelid movement, increased number of blinks, yawning, nodding and gazing. Using an imaging device pointing towards the operator, machine learning and computer vision can be used to detect these characteristics and perform drowsiness detection. This method benefits from the fact that it is non-intrusive and is not affected by road conditions or driving speed when it is performed on drivers.
In one study [5], a system was developed that monitors drowsiness through yawn detection. This method proved successful but resulted in false alarms in cases where operators were tired but not drowsy. Another problem was that operators often covered their mouths while yawning, obstructing the view of the camera. Another study [6] was performed where multiple features were calculated from the faces of drowsy operators in order to determine which features result in the best drowsiness classification. The accuracy of the calculated features is shown below. It is clear that fixed gaze and percentage of eye closure over time (PERCLOS) are the best features for drowsiness detection with an accuracy of 95.6% and 93.1% respectively.                Fixed Gaze: Accuracy: 95.6%        PERCLOS: Accuracy: 93.1%        Eye Closure Duration: Accuracy: 84.4%        Blink Frequency: Accuracy: 80%        Nodding Frequency: Accuracy: 72.5%
The inventor identified a need to integrate and improve the methods and systems to detect drowsiness with improved accuracy and to take immediate action upon detecting drowsiness of an operator thereby to reduce accidents related to drowsiness of an operator.


A method of manufacturing footwear includes providing a modular forepart and a modular rearpart, overlapping these parts along an overlap margin a preselected distance, and permanently joining the parts to selectively manufacture footwear of at least two different sizes, for example, a full size or a half size or some other partial size. The forepart and rearpart can be injection molded from one or more polymeric materials in a mold. The polymeric materials can be bonded to a sheet of material which can be at least partially retained in a three-dimensional, contoured shape by the polymeric material. The molded polymeric material can form a supportive and/or structural exoskeleton in an upper portion of the footwear. The exoskeleton can define one or more holes through which the sheet is visible to form one or more aesthetic regions on the upper. An article of footwear constructed with the method is also provided.

The present invention relates to footwear, and more particularly, to a method for manufacturing footwear.
Most conventional footwear includes an upper, within which a wearer's foot is positioned, and a sole, which generally forms a ground contacting, wear layer positioned beneath the wearer's foot. The upper and sole are usually separately manufactured, then joined with one another to complete the footwear.
Each footwear model typically is constructed in a wide variety of standard shoe sizes to ensure that the model can be offered to and fit a significant cross section of potential footwear consumers. There are a variety of different sizing systems to characterize "standard" shoe size measurements, for example, the U.S. system, the English system, the Parisian system, the Mondopoint system and the Asian system. Usually, these systems have shoe sizes that are divided into full and partial sizes, for example, under the U.S. system, the standard sizes usually are provided in full sizes, such as 8, 9, 10, etc., as well as half sizes, such as 8½, 9½, 10½, etc., to closely approximate and fit well a wearer's foot.
To make such a wide variety of sizes for a particular footwear model, manufacturers typically have to produce multiple different uppers and multiple different outsoles for each full shoe size and for each corresponding half shoe size. For example, for a single footwear model, a first upper pattern is created for a U.S. size 9½ shoe, and a second upper pattern is created for a U.S. size 9 shoe (along with all other desired sizes). Likewise, a first sole mold is created to mold a sole of proportionate size and shape to the U.S. size 9½ first upper pattern, and a second sole mold is created to mold another, different sole of proportionate size and shape to the U.S. size 9 second upper pattern. Accordingly, two separate lasts typically are used to construct the two different upper patterns, and two separate molds are used to mold the two different outsoles to create the two different sized shoes corresponding to the same footwear model.
The extra set of molds and lasts, and related retooling and operation, for the different soles and uppers can create a significant cost and labor burden on manufacturers. Basically, for each footwear model that has full U.S. shoe sizes 2 through 13 and corresponding half sizes, 2½ through 13½, the manufacturer might invest in, make and dedicate 24 different lasts for uppers and 24 different molds for corresponding soles. Again, this can result in a significant investment just to produce a given footwear model.
Another issue with most footwear is that the upper is constructed from multiple individual pieces of material. Those pieces are cut from stock material and usually modified in thickness for the particular footwear. Then they are joined with one another typically by stitching or cementing to form a three-dimensional upper. The pieces of the upper also are shaped over a last to better define the shape of the upper. After the pieces of the upper are assembled, a liner typically is then joined with them, again with more stitching or gluing. If the footwear is to include laces, eyelets must be formed on the upper.
All of the foregoing steps require substantial labor input. Moreover, the amount of labor required is compounded by the fact that every time a new footwear model and its various shoe sizes are desired, the manufacturing method must be retooled to accommodate the variations. Unfortunately, while many have tried to address the labor intensity issues concerning footwear, they remain as much a problem now as they did at the turn of the century.
Accordingly, there remains much room for improvement to provide a footwear manufacturing method and related footwear that is flexible enough to accommodate multiple models and sizes of footwear, and that generally reduces the amount of labor and time input for manufacturing the footwear.

Injection molded footwear and related method of manufacture


The present invention relates to a highly concentrated solution preparation of antagonistic anti-CD40 antibody, in which occurrence of turbidity or insoluble foreign matter attributed to antibodies is suppressed to a level equivalent to that of the conventional low-concentration lyophilized preparation.

In recent years, many therapeutic antibody drugs have been developed and anti-CD40 antibody can be mentioned as one of the antibodies. CD40 is an antigen that is expressed on the surface of B cell, DC, macrophage, endothelial cell, epithelial cell or tumor cells thereof, and anti-CD40 antibodies acting on CD40 are largely classified into agonistic one (also called "agonistic antibody") and antagonistic one (also called "antagonistic antibody"). B cell activation is known as an action of the agonistic antibody, and this antibody may be exemplified by an agonistic anti-CD40 antibody that is described in Patent Literature 1.
On the other hand, because CD40 plays an important role in immune responses, it is expected that immunosuppression for organ transplantation and therapeutic agents for autoimmune diseases can be developed by inhibiting the binding of CD40 and its ligand using the antagonistic antibody. In this case, antagonistic anti-CD40 antibody is required to inhibit the binding of CD40L to human CD40 and also, the antibody itself is required not to activate CD40.
Until now, many studies have been made on the anti-CD40 antibody, but most of the identified anti-CD40 antibodies are agonistic antibodies, and there are very few antagonistic antibodies identified, such as 4D11 (Patent Literature 1), 5D12 (Patent Literature 2) or the like. Among them, a modified 4D11 antibody (hereinafter, referred to as "4D11G4PE") is disclosed in Patent Literature 3, and this modified antibody avoids expression of agonistic activity both in vitro and in vivo, compared to the original 4D11 antibody. For this reason, this modified antibody is expected to be very useful as the antagonistic anti-CD40 antibody in the immune suppression for organ transplantation or in the treatment of autoimmune diseases (Patent Literature 3).
By the way, the development of these therapeutic antibody drugs requires a specialized formulation technology, as well as a technology of modifying the antibody itself. In other words, proteins such as antibodies or the like have a high molecular weight, a plurality of different functional groups, and a complex three-dimensional structure, unlike the conventional chemical synthetic molecules. Therefore, when therapeutic antibodies are formulated, there is a demand for a technology of storing the antibodies while maintaining their three-dimensional structure and their biological activity or characteristics.
One of these antibody preparations is, for example, a lyophilized preparation as described in Patent Literature 4. However, the lyophilized preparation requires a complex preparation procedure for administration to impose a burden on the practitioner in the medical field, and concerns are also raised about the risk of bacterial contamination due to handling. On the contrary, a solution preparation requires a simple preparation procedure before administration, and thus the risk of bacterial contamination is reduced. In the medical field, therefore, the solution preparation is considered more preferable than the lyophilized preparation.
For medical use, antibody is generally administered via an intravenous or subcutaneous route. Of them, subcutaneous administration of injectable preparations or the like is sometimes performed because of administration convenience or the like. Since subcutaneous administration depends on the volume limit (typically 1.5 ml or less) and the required administration dose (typically 50 mg or more), it is often necessary to administer a high concentration antibody.
For example, when 2 mg/kg of antibody is administered to a patient every week and the average body weight of the patient is 70 kg, the administration dose of the antibody is 140 mg, and the antibody concentration for subcutaneous administration should be approximately 100 mg/ml (in this case, approximately 140 mg of antibody is contained in 1.4 ml).
However, the highly concentrated antibody preparation has several problems. One of the problems is occurrence of turbidity or insoluble foreign matter attributed to antibodies during treatment and/or preservation.
Non-Patent Literature 1 suggests that a high concentration protein preparation shows an increase in the viscosity and turbidity, and ionic strength affects the degree. Further, Non-Patent Literature 2 suggests a method for stabilizing high concentration antibodies by spray-drying.
However, Non-Patent Literature 1 does not propose a fundamental solution for suppressing viscosity and turbidity of the high concentration protein preparation. Further, in the spray-drying described in Non-Patent Literature 2, a complex preparation procedure for administration is also required to impose a burden on the practitioner in the medical field, and concerns are also raised about the risk of bacterial contamination due to handling, like in the lyophilized preparation.
The known solution preparation of anti-CD40 antibody is a solution preparation of 4D11 antibody that is described in Patent Literature 5, and stability of this preparation has been confirmed in a variety of tests. However, because this preparation has the antibody concentration of 10 mg/ml, it is hard to use this preparation as the solution preparation for subcutaneous administration.

Highly concentrated anti-CD40 antibody pharmaceutical preparation


The invention relates to a welding band for welding synthetic resin film including a steel band, which is coated in its end parts with a thin copper layer. To attain the aim of improving the working life of such a welding band, the thin copper layer is covered with an even thinner metallic layer, preferably of nickel.

Welding bands are utilized in equipment for the welding of synthetic resin film as is for instance described in European patent publication 0 155 548 B1. In this equipment, continuous webs of film, for example tubular webs, are welded into bags. The correspondingly folded film web is conveyed until the point to be welded is located between suitable welding jaws. The welding band is arranged on the welding jaws and is in the form of a resistance heating element. The welding band is heated and the film web to be welded is clamped between the opposed welding jaws. The heat of the welding band is transmitted to the film so that it is welded.
The welding band consists of a narrow steel band or tape. A TEFLON band extends between the welding band and the film web to be welded. This TEFLON band extends over the entire welding jaw, that is to say beyond the edge of the film web to be welded. If the entire welding band is manufactured of steel, there will be local overheating in the edge portion of the tubular film web so that there may be damage to the TEFLON bands or even short-circuiting. As a remedy in this respect it has already been proposed to coat the end parts of the welding band with a thin copper layer, which provides satisfactory thermal and electrical conductivity. Owing to this improved thermal conductivity local overheating of the welding band is prevented.
If such welding bands are utilized for weldingly sealing bags filled with corrosive substances, as for instance salts, there is the problem that after a relatively short period of use, the copper layer is lost owing to corrosion. This in turn leads to local overheating of the welding band and, as a result, damage to the TEFLON tape.


An automatic calibration system for a second-order gradient microphone is provided to ensure optimum sensitivity balance between a pair of first-order gradient microphones mounted in a housing and forming the second-order gradient microphone. Automatic calibration is achieved through use of a transducer also mounted in the housing and located equidistant acoustically between the two first-order gradient microphones. Under the control of a computer, the transducer is directed to generated sound pressure which is used to calibrate the gain of amplifiers respectively associated with each one of the first-order gradient microphones for obtaining maximum directional sensitivity for a second-order directional response pattern. Such a system not only allows the use of inexpensive, non-matched microphones, but also obviates the need for factory calibration. Since the system is configurable to optimize itself automatically prior to use, calibration may be maintained regardless of aging, environmental stresses and parts replacement.

1. Technical Field
This invention relates to directional microphones and more particularly, to an improved apparatus and method for calibrating these microphones.
2. Description of the Prior Art
Gradient microphones have been used for some time to selectively accept sound energy from a desired direction while excluding or attenuating sound energy from other directions. Recently, a class of gradient microphones has been developed which utilize two gradient (differential) microphones located along an axis to further enhance the directionality effects. Such microphone systems frequently employ an electronic delay at the output of one of two first-order gradient microphones whose output is then combined with the output of the second. One arrangement of such a system is described by G. M. Sessler, J. E. West and R. A. Kubli, Unidirectional, Second-Order Gradient Microphone, J. Acoust. Soc. Am., Volume 86, No. 6,2063-2067 (December 1989).
The attractiveness of second-order microphone systems is currently diminished by their relatively complicated mechanical and electrical design requirements. These microphone systems have a tendency toward performance degradation if the sensitivity of the two first-order microphones which comprise the compound second-order microphone system differs by more than a small amount. The degradation appears as a reduction of the microphone's directionality, accompanied by the appearance of undesirable side and rear lobes. There is a need, therefore, to obtain closely-matched first-order microphones and/or to carefully calibrate the associated microphone preamplifiers to achieve near-exact gain balance. Both of these approaches are costly. To obtain microphones matched to the degree of accuracy required (better than 0.5 dB), large numbers of microphones must be accurately calibrated and sorted into "bins", whose contents may then be sold as matched. Since this process involves the testing of many microphones to high accuracy, the use of matched microphones results in high system cost.
Alternatively, microphones less well-matched may be used with microphone preamplifiers whose gain can be accurately adjusted to compensate for the microphone mismatch. This process requires specialized equipment, an anechoic environment, and hand labor to perform the adjustment. The procedure involves use of a point sound source located in the far-field, in line with the axis of the microphone. With the rear null of the microphone pointed toward the source, the gain of the preamplifier connected to one of the first-order microphones is adjusted to minimize the output of the composite microphone.
Both of these alternatives still have limitations: As the microphones and amplifiers age, their sensitivity and gain may change unpredictably. Effects such as mechanical shock, temperature, humidity, and operating voltage may also contribute to loss of matching accuracy. This opens the possibility that even with exact factory calibration, microphone quality may degrade over time.

Automatic calibrating apparatus and method for second-order gradient microphone


An ink composition for a pressurized ballpoint pen and a pressurized ballpoint pen which can exhibit excellent writing properties, do not cause ink leakage and which are suited to handwriting. The ink composition for a pressurized ballpoint pen includes at least a colorant, a solvent and silica, wherein a coagulated matter containing at least the silica is contained therein, and the ink composition has a viscosity of 10000 to 40000 mPa·s at 25° C. A pressurized ballpoint pen equipped with a refill, in which pressurized gas is charged into an ink reservoir charged with the ink composition for a pressurized ballpoint pen and a closed vessel containing the reservoir is also set forth.

In general, known as a ballpoint pen are a gravity type (free atmospheric type) ballpoint pen comprising a ballpoint pen tip, an ink reservoir and an ink filled thereinto and a so-called pressurized type ballpoint pen in which pressurized gas such as nitrogen gas is charged into an ink reservoir filled with an ink and a closed vessel containing it.
The above pressurized type ballpoint pen has the advantages that upward writing is possible and that an ink having a specific function can be used, but an ink reservoir charged with an ink is always pressurized, so that a small amount of the ink is apt to leak from a pen tip.
In order to prevent the above matter, an apparent viscosity of an ink has to be raised, and this brings about the problems that a write feeling becomes heavier and it takes time to charge an ink reservoir with an ink and that the ink is liable to be stuck onto the inside of the ink reservoir, that is, a so-called clear drain property is inferior.
On the other hand, it is described in Japanese Patent Publication No. 48565/1972 that the main point is to prepare a writing instrument in which an ink or a fluid is not allowed to flow out in the vicinity of a ball of the ballpoint pen tip in the form of a pressurized writing or marking instrument, and disclosed therein is a ballpoint pen writing instrument characterized by that a writing fluid for the above writing instrument comprises at least one solvent, one colorant and at least one polymer which is soluble in the above solvent and which can provide the above fluid with a viscoelasticity, a strong coagulating property, a strong sticking property, a fluid resistance and a film-forming property together with the other components for the writing fluid, wherein the above writing fluid has a viscosity of 100000 cps or more (measured at 25° C. and 0.3 rpm using a fifth cylindrical spindle in a Brookfield LMT viscometer), and a cross-linking carboxypolymethylene type polymer or polyvinylpyrrolidone type polymer or both of them is used as the above polymer.
Further, a thixotropic ink for a pressurized ballpoint pen containing higher fatty acid soap is disclosed in Japanese Patent Application Laid-Open No. 096336/1975, and the viscosities of 600000 cps and 800000 cps are given in the examples.
Further, an ink composition having metallic gloss which is set to a viscosity of 50000 cps or more is disclosed in Japanese Patent Application Laid-Open No. 186574/1985. Also, an ink for a pressurized ballpoint pen used for a plotter is disclosed in Japanese Patent Application Laid-Open No. 7775/1987, and it is described that the viscosity thereof falls preferably in a range of 40000 to 500000 cps.
However, any ink compositions for pressurizing disclosed in the respective official gazettes described above have a high viscosity, and there still remain the problems described above, that is, the problems that an ink leaks from a pen tip is small amount; a write feeling becomes heavier; it takes time to charge an ink reservoir with an ink; an ink is liable to be stuck onto the inside of an ink reservoir, and a so-called clear drain property is inferior, and so on.
On the other hand, an oil-based ink for a ballpoint pen containing silica having a primary average particle diameter of 7 to 40 nm is disclosed in Japanese Patent Application Laid-Open No. 195365/1998 which is a prior art applied by the present inventors.
In the above prior art, however, it is described in the specification that "a pen body rises in a temperature when exposed to direct sunlight or an ink leaks from a pen tip in a certain case when left standing downward for long time", and it is a technique related to a gravity type (free atmospheric type) ballpoint pen. More specifically, it is described that a content of silica is 0.01 to 2.0% by weight, preferably 0.03 to 1.0% by weight, and it is 0.3% by weight, 1.0% by weight, 0.05% by weight and 0.5% by weight respectively in order in Examples 1 to 4. A supplementary examination carried out by applying ballpoint pens specifically described in Example 2 (1.0% by weight) and Example 4 (0.5% by weight) to pressurized ballpoint pens under the same conditions as in examples described later has made it clear to bring about the problem that an ink leaks from a pen tip. Further, observation of the above oil-based ink under an optical microscope has shown that coagulated matters containing silica are not found and that the ink stays in a homogeneous state. Accordingly, the oil-based ink described in the above official gazette is different from the ink of the present invention in uses, recognition of the problems and ink physical properties.
In light of the problems on the conventional techniques described above, the present invention intends to solve them, and an object thereof is to provide an ink composition for a pressurized ballpoint pen and a pressurized ballpoint pen, wherein an ink is prevented from leaking from a pen tip; a write feeling is excellent; time for charging an ink reservoir with the ink can be shortened; and a clear drain property is excellent as well.

Ink composition for pressurized ball-point pen and pressurized ball-point pen