The present invention provides means and methods for noninvasively identifying the blood pressure characteristics in each of the seven types of vessels in the circulatory system, including the central venous pressure (CVP) through a single monitoring system using fluid depletion plethysmography. Known pressure is applied to a body region in increasing amounts to force blood volume from the body region in step-wise fashion through each vessel type. Blood volume depletion for each vessel type is measured by the increasing electrical impedance of the body part during depletion and is plotted against the increasing pressure data. The resulting series of slope changes within the plotted curve reveals the blood pressure for each vessel type. The data obtained may further be used to determine vessel wall compliance/tension as well as standard measurements such as pulse and large artery systolic and diastolic pressure. Release of the applied pressure may then yield similar data by measuring blood volume replenishment against the decreasingly applied pressure during the same diagnostic operation. The method is not dependent on oscillometric or pulsatile measurement methods. The electrical leads of the impedance/volume sensor and the means for applying pressure to the body part are coextensive to ensure accurate indication of blood volume depletion and replenishment in the body region under pressure and may be incorporated into a single integrated structure.

1. Field of the Invention
The present invention relates to a method of noninvasive measurement of physiologic parameters in a subject. In particular the present invention relates to a method of noninvasive and non-pulsatile measurement of physiologic fluid parameters as well as a combination of nonpulsatile and pulsatile physiologic parameters for a subject, or patient, which may include any animal with body fluid compartments.
2. Discussion of the Related Art
Known art noninvasive methods have been disclosed for determining physiologic parameters such as arterial blood pressure (U.S. Pat. No. 4,178,918), pulse oximetry (U.S. Pat. No. 3,998,550), and vascular compliance (Shankar, U.S. Pat. Nos. 5,241,963 and 5,724,981) using pulsatile signals acquired from the subject. However, these methods are dependent upon and limited by naturally occurring pulsations in the arteries of the subject.
Other known art noninvasive methods have been disclosed for determination of vascular behaviors by rheoplethysmography (Piquard, U.S. Pat. No. 4,169,463) and determination of blood pressure in the veins and arteries (Blazek et al., U.S. Pat. No. 5,447,161) by observing non-pulsating signals acquired from the subject by a technique known as xe2x80x9cvenous occlusion plethysmography.xe2x80x9d This method relies upon a time-based accumulation of blood in the veins of the subject in order to make the physiologic measurements. However, these methods require that the occlusive device be proximal or downstream from the measuring device along the body region of the subject. Also, these methods further lack the ability to calibrate directly to the subject and rely upon coefficients of standardization, which are characteristic of the healthy vascular operation of a normal limb of the same type as the limb under study. In some instances, these methods are limited to application on fingers and toes.
Referencing Table 1 and FIGS. 1-2, the functional parts of the cardiovascular system include the heart, the lungs, the arteries, the capillary beds, the veins, and the blood. The cardiovascular system is comprised of two independent vascular circuits, the pulmonary circuit and the systemic circuit. Each vascular circuit has a system of arteries and a system of veins separated by a capillary bed. Blood is primarily a composite of plasma and red blood cells. The human heart is a four-chamber pump organized as a right half and a left half with two sequential pumping chambers in each half. The upper pumping chamber of the heart is called the atria and the lower pumping chamber of the heart is called the ventricle. The atria serve as filling chambers for the ventricles and contract prior to the time of contraction of the ventricle. This difference in time of contraction allows the atria to pre-load the ventricles prior to the ventricular contraction. The ventricles are the primary pumping chamber for each circuit. The right ventricle pumps blood into the pulmonary circuit and the left ventricle pumps blood into the systemic circuit.
Thus, the right half of the heart supplies blood flow to the pulmonary circuit and the left half of the heart supplies blood flow to the systemic circuit. Each circuit returns blood to the other side of the heart through its associated venous system. The pulmonary circuit is composed of the pulmonary arteries, the lungs, and the pulmonary veins. The pulmonary circuit oxygenates the blood in the lungs and returns the oxygenated blood to the left heart to be pumped into the systemic circuit. The systemic circuit, composed of the systemic arteries, the systemic capillary beds, and the systemic veins, supplies oxygenated blood to all areas of the body. The systemic blood flow is then returned to the right heart by the systemic veins.
The heart produces pulsatile blood flow in the arteries by forcing a volume of blood into the aorta during each contraction of the heart. This volume of blood, known as the xe2x80x9cstroke volumexe2x80x9d, causes an arterial pressure wave to propagate throughout the systemic arteries up to the arterioles (FIG. 1). The arterioles, which are the smallest arteries in the systemic circuit, have the ability to dynamically vary the resistance to blood flow (Table 1) in response to demands from the end cells of the body. This resistance to blood flow is known as the xe2x80x9cperipheral vascular resistancexe2x80x9d. The peripheral vascular resistance causes a reduction in arterial blood pressure as the blood flows through the arterioles into the capillary bed as shown in FIG. 2.
In particular, the arterial blood pressure before the arterioles is highly pulsatile and time variant, while after the arterioles, the arterial blood pressure is primarily steady state, lacking any significant pulsation. Generally, known noninvasive methods of measuring arterial blood pressure, pulse oximetry, and vascular compliance, rely upon the pulsation of arterial blood pressure. As shown in FIG. 2, the blood pressures that exist in the capillary beds and veins after the arterioles, is substantially non-pulsatile and therefore does not lend itself for measurement by known noninvasive pulsatile plethysmographic methods. Furthermore, other physiologic attributes such as oxygen saturation of the blood and compliance of the vessel wall in the non-pulsatile vessels cannot be determined by methods that are reliant on arterial pulsations.
Blood vessels have elastic walls that stretch in response to the volume of blood contained within them. The degree of elasticity or tension of the vessel wall determines how much pressure is produced within a vessel for a specific amount of blood volume or change in blood volume. The blood vessel wall is an active organ with the ability to vary its compliance, or its inverse, wall tension, as discussed below, dependent on sympathetic nervous stimulation to the vessel.
In arteries of the subject, there is both a steady state and a pulsatile time variant volume of blood in the vessel. This is due to the stroke volume of blood forced into the arteries by each contraction of the heart. The increased stroke volume of blood in the arteries caused by the heartbeat creates pulsatile pressure waves that propagate to a point of extinction within the arterial bed. The actual point of extinction of the pulsatile pressure wave can be dependent upon the physiologic state of the arteries of the subject but is generally thought to be in the small arteries and before the arterioles. The amount of arterial pulse pressure change that occurs during each cardiac cycle is dependent on: the elasticity of the arterial wall, the stroke volume produced by the heartbeat, and the peripheral vascular resistance of the systemic circuit.
The elasticity of the vessel is commonly referred to as the xe2x80x9cvascular compliancexe2x80x9d. Vascular compliance is defined as the rate of change of volume in the vessel versus the rate of change of pressure within the vessel. The inverse of compliance is called the vessel wall tension. Compliance and tension are in effect a measure of the level of elasticity or stiffness of the vessel wall. The loss of elasticity of the blood vessel wall contributes to the disease state known as hypertension or elevated blood pressure. It has been extensively reported in medical literature that both a thickening of the blood vessel wall (Atherosclerosis) as well as a plaquing of the interior lining of the blood vessel (Arteriosclerosis) contributes to a reduction in blood vessel elasticity and a general increase in arterial blood pressure. Furthermore, pathologies of the sympathetic nervous system and the adrenal medullae have been shown to dramatically affect the tension or compliance of the blood vessel wall.
The compliance of a vein is generally six to eight times greater than the compliance of an artery. Therefore, veins can accept and hold much larger volumes of blood at lower pressures than arteries. The tension of the vein wall and the volume of blood that it is containing regulate the venous blood pressure. The tension or compliance of the vein is regulated by the sympathetic nervous system. Body fluid volumes are primarily controlled by the function of the kidneys. A device that noninvasively determines the compliance or tension of the compartments throughout the circulatory system would be beneficial in the diagnosis and management of cardiovascular diseases.
Venous blood pressure is of particular interest to healthcare providers because it is a critical parameter in the diagnosis and treatment of a variety of diseases such as heart failure, acute myocardial infarction, pulmonary hypertension, renal failure, and deep vein thrombosis. Furthermore, it would be a valuable physiologic parameter in the triage of emergency care patients for detection of cardiovascular and hemodynamic distress.
Central venous pressure (CVP), also known as the right atrial filling pressure, is of particular interest in diagnosing and managing subjects afflicted with these disease states. Since Venous pressure is a low, substantially non-pulsatile, time invariant physiologic parameter, there has been no prior method demonstrated which directly measures its value noninvasively. Heretofore, CVP has been measured by the expensive and invasive surgical insertion of a transducing catheter into the subject. Therefore, the ability to measure noninvasive central venous pressure with an easy to use noninvasive device would have a substantial impact on the quality and cost of healthcare delivery.
Arterial blood pressure has been measured by both invasive and noninvasive methods in the known art. Invasive blood pressure monitoring requires the insertion of a catheter into an artery for direct transduction of arterial pressure data. Due to the invasive nature of this method, it is considered a separate art and will not be further reviewed here. Two primary known methods of noninvasive arterial blood pressure monitoring, the auscultatory method and the oscillometric method, are discussed below.
The conventional auscultatory method of non-invasive blood pressure (NIBP) monitoring relies upon the sounds made by the blood coursing through a partially restricted artery. A clinician, e.g. a physician, a nurse, a medical technician or a paramedic, wraps a blood pressure cuff around the limb of the subject and inflates the bladder that is built into the cuff to exert on the arm a counter-pressure that exceeds the subject""s systolic blood pressure and consequently occludes the flow of blood through the arteries in the limb. The clinician then slowly releases the cuff pressure while simultaneously observing the pressure indicated by a cuff pressure indicator and listening through a stethoscope for the so-called Korotkoff sound generated within the lower brachial artery. The Korotkoff sound is absent when the bladder counter-pressure is above systolic or below diastolic pressure. The onset of the Korotkoff sound is taken as indicating systolic pressure and the subsequent disappearance of the Korotkoff sound is taken as indicating the diastolic pressure.
The auscultatory method is subject to disadvantage because it requires that a clinician listen for the Korotkoff sound. Further, the precise point of the onset and disappearance of the Korotkoff sound are somewhat subjective and accordingly two clinicians can provide significantly different blood pressure values for the same subject. In addition, unless the clinician releases the cuff pressure slowly in the region of the systolic and diastolic pressures, it is difficult to relate the onset and disappearance of the Korotkoff sound precisely to pressure values. Moreover, the mean pressure cannot be reliably measured directly by the auscultatory method since there is not a definitive sound to identify the mean pressure value. The clinician may estimate the mean pressure from the systolic and diastolic pressures based on knowledge of the typical blood pressure waveform.
The wall of a blood vessel of a subject is elastic and therefore is distended cyclically when pressure waves induced by cardiac activity propagate through the vessel. When an external counter-pressure is applied to a limb of a subject by a cuff bladder circumscribing the limb, the pressure within the bladder is communicated through the tissue bed and fluids of the limb to the wall of the arteries within the limb.
Conversely, the pressure wave within the artery generated by the heart contraction is communicated through the arterial wall, tissue bed and fluids of the limb into the bladder and the fluid in the bladder. Consequently, the pressure of the fluid in the bladder is modulated by the subject""s vascular pressure changes in the limb. These modulations of pressure within the bladder are commonly referred to as oscillations.
The variation in amplitude of the pressure changes induced in the bladder can be measured and is used in the oscillometric method of noninvasive blood pressure monitoring. The amplitude of each oscillation is recorded versus the value of cuff counter-pressure at which it occurred. In the oscillometric method, the cuff bladder is inflated to a pressure above systolic and the cuff pressure is gradually released, as in the case of the auscultatory method, and during the release of cuff pressure the amplitude of pressure variations in the bladder are measured.
The bladder pressure value is filtered, mathematically or electronically or the like, to separate the oscillating and steady-state components of the bladder pressure. The oscillating and steady-state pressure components are amplified and recorded separately. The magnitude of the steady-state component is a measure of the counter-pressure applied to the limb by the bladder while the oscillating component is used to develop the oscillometric complex from which can be determined the mean, systolic, and diastolic pressure values of the subject.
The oscillating component waveform has a characteristic shape, being composed of oscillations at pulse rate within an envelope that initially increases in amplitude then declines to a minimal value, as shown in FIG. 3. The characteristic sequence of oscillations of increasing and decreasing peak-to-peak amplitude versus counter-pressure is known as the oscillometric complex. Since the maximum change in bladder pressure occurs when the counter-pressure is equal to the mean blood pressure, the mean blood pressure is equal to the counter-pressure at which the pressure wave oscillations reach their maximum amplitude.
The maximum peak-to-peak amplitude is multiplied by a derived factor X to define a systolic detection amplitude and by a derived factor Y to define a diastolic detection amplitude. A search algorithm examines the oscillations of the oscillometric complex, starting from the mean detection point and moving towards higher counter-pressure, to identify the first pulse of peak-to-peak amplitude less than the systolic detection amplitude and defines the occurrence of this pulse as the systolic detection point. Similarly, the search algorithm examines the pulses of the oscillometric complex, starting from the mean detection point and moving towards lower counter-pressure, to identify the first pulse of peak-to-peak amplitude less than the diastolic detection amplitude and defines the occurrence of this pulse as the diastolic detection point. The counter-pressure associated with systolic detection point is reported as the systolic pressure and the counter-pressure associated with the diastolic detection point is reported as the diastolic pressure. The oscillometric method thusly determines the mean blood pressure and estimates the systolic pressure and the diastolic pressure.
The advantage of oscillometry, i.e. the oscillometric method, is that it is easily automated and can serve to take repeated intermittent blood pressure measurements over relatively short periods of time, such as once per minute.
Body Fluid Compartmentsxe2x80x94Volume and Status Monitoring
Fluids within the body of a subject are referred to herein as compartmentalized in vascular and nonvascular, and in some instances extracellular fluid and intracellular fluid, compartments. The extracellular fluid compartment contains all fluids that exist outside of cells and include interstitial fluid, blood, plasma, lymph, cerebrospinal fluid, intraocular fluid, gastrointestinal fluid, and fluids of the potential spaces. Intracellular fluids are all fluids contained within cells of the body including the red blood cells. In general, 60% to 70% of the total body fluid in a subject is contained within the cells of the subject with the remaining fluid being contained in extracellular fluid compartments such as the various vascular vessel types, each of which is deemed a different compartment for purposes of explanation herein. Understanding the distribution of body fluids in each vascular, nonvascular, intracellular or extracellular fluid compartment can be indicative of disease states of the subject and means and method for doing so would be a desirable addition to the art.
A plethysmograph measures a change in volume and records the changing value. Plethysmography has been utilized in physiologic monitoring to measure the respiration rate, the oxygen saturation of blood, and the pulse volume in arteries. Various methods of plethysmography have been provided in known art including volume plethysmography, impedance plethysmography (e.g., Shankar, U.S. Pat. Nos. 5,241,963 and 5,724,981), which are forms of pulse plethysmography and venous occlusion plethysmography (e.g., Piquard, U.S. Pat. No. 5,169,463, supra.). As evidenced in the art, the plethysmograph, independent of sensing modality, measures a time rate of increase or decrease in volume within the subject.
Volume plethysmography is a method of noninvasive physiologic measurement described by Shankar for measuring the volume of arterial pulsations in the limbs of a subject. Shankar provides a method of measuring pulse volumes from the arteries of subjects and relating that information to the state of atherosclerosis of the arteries. This plethysmographic method is reliant upon arterial pulsations generated within the body of the subject and therefore is incapable of measuring the physiologic characteristics of vessels of the body which do not contain pulsatile flow.
Venous occlusion plethysmography is a method of noninvasive physiologic measurement reliant upon the accumulation of fluids in the veins of a body region that is distal or upstream from a venous occlusion device. Reference for Venous Occlusion Plethysmography is made to xe2x80x9cPrinciples of Applied Biomedical Instrumentationxe2x80x9d, 3rd Ed, L. A. Geddes, L. E. Baker, John Wiley and Sons, 1989. The venous occlusion device must be capable of applying a pressure that is greater than the venous pressure and less than the arterial pressure to the body region in order to cause a time variant accumulation of venous blood in the upstream-monitored body region of the subject. It will be noted that xe2x80x9cupstreamxe2x80x9d is determined according to the area of higher fluid pressure, and in this instance as relative to the occlusion, although upstream may be the physically distal position of the body limb.
Because venous occlusion plethysmography relies upon the accumulation of fluid in the upstream body region of the subject (again relative to the occlusion), the method is limited to closed body regions such as limbs, legs, arms, fingers, and toes. Physiologic parameters are measured by plethysmographic methods from the accumulating fluids during the period of venous occlusion. A problem with this method is that the physiologic measurements are made on a body region that is being altered from its natural state prior to determination of the desired physiologic parameters. As abnormal fluid volumes accumulate in the fluid compartments of the upstream body region, fluid pressure increases above normal and venous compliance decreases below normal. These abnormal conditions can introduce errors and uncertainty in the physiologic measurements.
Impedance plethysmography is the measurement of impedance changes in a subject by measuring the time variant electrical impedance of the subject and determining volume characteristics based upon measured impedance values. Known impedance plethysmographic methods have largely been limited to the measurement of impedance changes caused by pulsatile, or time varying, volume changes in the arteries of the subject and to venous occlusion plethysmography which depends upon a separation between the pressure applying device and the impedance sensing device.
The ability to non-invasively measure volumetric changes in the vascular bed by impedance plethysmography has been extensively discussed in the literature including Nyboer, J., xe2x80x9cElectrical Impedance Plethysmography: A Physical And Physiologic Approach To Peripheral Vascular Study.xe2x80x9d Circulation, 2:811-821, 1950; Geddes, and Sadler, xe2x80x9cThe Specific Resistance Of Blood At Body Temperature.xe2x80x9d xe2x80x94Med. Biol. Eng. 11(3):336-339, 1973; Shankar, Webster, and Shao, xe2x80x9cThe Contribution of Vessel Volume Change and Blood Resistivity Change to the Electrical Impedance Pulsexe2x80x9d, IEEE Transactions on Biomedical Engineering, Vol. BME-32, No. 3, Mar. 1985; Chumlea, Guo, Baumgartner, and Siervogel, xe2x80x9cDetermination Of Body Fluid Compartments With Multiple Frequency Bioelectric Impedance.xe2x80x9d xe2x80x94Human Body Compositionxe2x80x94In Vivo Methods, Models, and Assessment, Plenum Press, Basic Life Sciences Vol. 60; Shimazu, Yamakoshi, Togawa, and Fukuoka, xe2x80x9cEvaluation Of Parallel Conductor Theory For Measuring Human Limb Blood Flow By Electrical Admittance Plethysmographyxe2x80x9d, January 1981, IEEE Transactions on Biomedical Engineering; xe2x80x9cEncyclopedia of Medical Devices and Instrumentationxe2x80x9d, Volume 3, pg. 1633, 1988, John Wiley and Sons, New York; Nyboer, xe2x80x9cElectrical Impedance Plethysmography,xe2x80x9d 2nd Edition, Thomas Books, Springfield, Ill., 1970; and Lifshitz, xe2x80x9cElectrical Impedance Cephalography, Electrode Guarding And Analog Study,xe2x80x9d Ann. N.Y. Acad. Sci. 170:532-549, 1970.
Impedance monitoring is based upon the relationship E=I*R, known as Ohm""s Law, which states that the voltage drop (E) across a length of conductor is equal to the current flowing through the conductor (I) times the resistance of the conductor (R). When the current is an alternating current (AC), the resistance element becomes a vectorial sum of a real component (R) as well as an imaginary component (jX) and is referred to as impedance. The complex nature of impedance arises from the presence of capacitance or inductance in the conductive material. The impedance (Z) of a conductor is represented as a complex number (Z=R+jX) composed of the resistance (R) and reactance (jX) of the conductor. Furthermore, the admittance (Y) of a substance is equal to the inverse of the impedance or 1/Z of that substance. The phase angle ( ) of impedance (Z) is the TANxe2x88x92(jX/R).
Nyboer was the first to apply the formula for the resistance of a homogeneous volume conductor to predict the relationship between impedance changes and blood volume changes. The electrical impedance (Z) of a body region (b), can be expressed in terms of its cross sectional area (acs), length (L), and resistivity ( ) of the material.
Zb=bL/acsxe2x80x83xe2x80x83(1)
acs=bL/Zbxe2x80x83xe2x80x83(2)
acs=bLYbxe2x80x83xe2x80x83(3)
Since the volume of a vessel segment is Vb=L*acs, then the electrical impedance can be expressed in terms of the segmental or regional volume which can be expressed in terms of the electrical impedance as shown in equations 4 and 4a respectively.
Zb=bL2/Vbxe2x80x83xe2x80x83(4)
Vb=bL2/Zbxe2x80x83xe2x80x83(4a)
Nyboer further assumed that the segmental blood volume change (V) could be modeled as the impedance change (Z) due to the change in blood volume electrically in parallel with the basal tissue impedance Zt (see FIG. 4). This led to the well-known xe2x80x9cNyboer Formula,xe2x80x9d
Vb=xe2x88x92bL2Zb/Zt2xe2x80x83xe2x80x83(5)
This relationship between the change in volume of blood and its associated change in impedance is the basis of impedance plethysmography. The Nyboer formula has been widely practiced in the known art with mixed results.
The Nyboer formula is dependent upon a changing impedance value (Zb) in order to determine a changing volume (Vb) within the body of the subject. Further, the knowledge of the specific value of b for the particular subject is critical to the accuracy and reliability of the volume data determined by the Nyboer formula. It is further known that the resistivity of blood is dependent on the hematocrit of the particular subject and therefore will vary from subject to subject.
In the Nyboer formula (5), it is assumed that all elements are constant except Zb indicating the pulsatile volume changes in the arteries. This assumption is only true if there are no other concurrent material volume changes occurring in the monitored body region of the subject. However, in practical applications of impedance plethysmography, this assumption is often not true and therefore the Nyboer formula can often generate unreliable and inaccurate results due to respiration and motion artifacts in the impedance data.
Further, the Nyboer formula assumes a composite resistivity for the diverse elements that comprise Zt. This composite resistivity may vary from subject to subject and contribute uncertainty to the volume values derived using the Nyboer formula. It is important to note that even though the Nyboer formula has been widely used in the measurement of physiologic parameters, the Nyboer methodology has been criticized by some practitioners as being unreliable and inaccurate.
It is generally known that a body region of the subject is composed of a variety of conductive materials including fluids, tissue, fat, and bone. It is further known that cell membranes and vessel walls surrounding fluids may affect the conductivity of the cells and vessels. Therefore, a body region of the subject is considered a composite conductive medium with multiple current pathways through the body region. Each conductive pathway is considered to have unique electrical conductivity characteristics. The xe2x80x9cParallel Conductor Theoryxe2x80x9d describes the subject as a parallel conductor model composed of various conductive elements that represent different materials of the subject""s body composition. The parallel conductor hypothesis models a body region as a set of parallel conductors in which the volume of arterial blood in the body region is the only time variant conductor in a compliant subject.
The parallel conductor model shown in FIG. 5 is composed of a constant admittance value (Yt) that represents the composite parallel conductance characteristics of all the non-changing conductive pathways in the body region, and a pulsed changing value (Ybv) that represents the pulsatile or time changing volume of arterial blood in the body region. Yt represents the total admittance value of all non-changing elements in the body region including fat, bone, lean tissue, extracellular fluid, intracellular fluid, and nonpulsatile blood volumes in the body region. Ybv represents the admittance of the variable arterial blood volume. This model is consistent with the simplified Nyboer formula (FIG. 4).
However, the parallel conductor model may also be expressed to show the total admittance of a body region by modeling each conductive element in the body region as parallel conductors:
YT=Ybv+Ybc+Yvc+Yof+Ytis+Ybone+Yfat (admittance form)xe2x80x83xe2x80x83(6a)
Or the total impedance of the body region by parallel impedances:
1/ZT=1/Zbv+1/Zbc+1/Zvc+1/Zof+1/Ztis+1/Zbone+1/Zfatxe2x80x83xe2x80x83(6)
In a parallel impedance network in which the blood is a single element of a complex system of conductive elements, it would be valuable to be able to isolate the affects of the various impedance elements on the measured composite impedance value. Applicants do not believe that the known art has taught this valuable principle.
Photo-Plethysmography is a known method of measuring the characteristics of blood and tissues by the amount of absorption of particular wavelengths of light. See for example U.S. Pat. No. 5,447,161 to Blazek et al, which combines venous occlusion and photo plethysmography techniques.
To applicants"" knowledge, none of the aforementioned known art has recognized that information on the entire vascular system may be gained by combining plethysmography with the depletion or replenishment of body fluids under controlled conditions.
Upon gaining an understanding of the foregoing discussion, the person having ordinary skill in the art will appreciate that the circulatory system, in all its components, is connected, interactive, interdependent and largely unexplored or monitored outside of its large or pulsatile, or both, components, such as the heart and large veins and arteries. Therefore what is needed are means and methods for gathering physiologic data on each part of the circulatory system for gaining further knowledge of the operation of the circulatory system, including each vascular compartment or chamber or vessel type, including the large arteries, small arteries, arterioles, capillaries, venules, small veins and large veins. It is further desirable that such means be non-invasive, easily utilized and inexpensive when compared to the high cost of invasive techniques.
The present invention provides means and methods for gathering physiological parameters, or data, on each part of the circulatory system, thus affording opportunity for gaining further knowledge of the operation of the circulatory system, including each vascular compartment or body fluid chamber, or vessel type, including the large arteries, small arteries, arterioles, capillaries, venules, small veins, large veins and nonvascular fluids. It is the inventors"" belief that as such means provide for increased knowledge of the parts and behavior of the circulatory system, other fluid compartments or physiologic data of significance may be identified. The present invention provides such means in a non-invasive manner which is easily utilized and is inexpensive when compared to the high cost of invasive techniques.
The present invention provides means and methods for noninvasively identifying the blood pressure characteristics in each of the seven types of vessels in the circulatory system, including the Central Venous Pressure (CVP), through a single monitoring system. According to certain aspects of the invention, a known pressure is applied to a body region in increasing amounts to force blood volume depletion from the body portion in step-wise fashion through each vessel type. Nonvascular fluid compartment parameters may also be identified. Fluid volume depletion, or replenishment, or both, for each compartment type is then tracked, or measured, in the pressurized area, e.g. by the increasing electrical impedance of the body part during depletion, or by other plethysmography techniques; and is plotted against the increasing pressure data. Pressure and volume data are then referenced against one another, such as by graphing or otherwise recording the data. Such a graph may be done virtually, e.g., mathematically, without the plotting of an actual curve. Release of the applied pressure may then yield similar data by measuring fluid volume replenishment, as indicated by decreasing impedance, against the decreasingly applied pressure during the same diagnostic session.
In the case of an actual graphing, the resulting series of slope changes witnessed within the plotted curve can be seen to reveal the characteristic blood pressure state in the range between each slope change, for each vessel type placed under depletion pressure. In the case of the virtual graphing, the apparatus may mathematically identify the points at which a coordinate linear, or curvilinear, relationship changes for the body fluid volume indications as referenced to the series of pressure values. That is, by detecting the change in the slope of the virtual graph, the state transitions, i.e. transitions from one pressure state to the next, are indicated in the vascular fluid profile between two adjacent vessel types (i.e. the transition points between vascular types).
The method is not dependent on oscillometric or pulsatile measurement methods. The measurement area for the volume sensor and the area of uniform pressure application to the body part are coextensive to ensure accurate indication of fluid volume depletion and replenishment and may be incorporated into a single integrated structure.
The present invention is not limited to the measurement of physiologic parameters in the large, and (to some minor extent) the small arteries. The present invention""s lack of dependency on sensing the natural pulsations of the subject eliminates the time dependency on the occurrence of the naturally occurring pulsation for the measurement of physiologic parameters and allows for determination of physiologic parameters in fluid compartments that are non-pulsatile or oscillometric in nature. The present invention further reduces or eliminates the confounding signals of motion artifact and respiration in the acquisition and processing of the acquired physiologic data.
The present invention overcomes limitations of venous occlusion plethysmography to identify various physiologic properties of the subject in non-venous vessels of the body such as capillary vessels, arteriolar vessels, and nonvascular fluids. The present invention improves the capability of noninvasive pressure and volume measurement instruments to observe the characteristic physiologic behaviors of the fluid compartments of the subject during the depletion of fluid, during static fluid, and during replenishment of fluid, in each of the fluid compartments of the body region of the subject. Furthermore, the present invention is not limited to use on an appendage of the body of the subject but may be applied to any body region of the subject containing body fluid compartments.
xe2x80x9cTransition Pointsxe2x80x9d, xe2x80x9cstate transitionsxe2x80x9d, and xe2x80x9cstate changesxe2x80x9d, are used synonymously to indicate a change from one pressure state (indicative of a particular fluid pressure and hence a particular vessel type according to aspects of the present invention) to a different pressure state.
xe2x80x9cKnown pressure valuexe2x80x9d as used herein includes known or measured values at the time of force application.
xe2x80x9cLinear relationshipxe2x80x9d as used herein includes curvilinear relationships for ease and simplicity of explanation, unless otherwise noted.
xe2x80x9cGraphingxe2x80x9d as used herein includes any physical or virtual representation or construct referencing one type of value against another type of value, unless otherwise noted.
xe2x80x9cUpstreamxe2x80x9d is used herein in the sense of an area of higher fluid pressure, while xe2x80x9cdownstreamxe2x80x9d indicates an area of lower fluid pressure.

Noninvasive method of measuring physiologic parameters


A new silicon carbide material is made following a procedure including hot pressing to provide a finished product having a microstructure with an optimal grain size of less than 7 micrometers. The material exhibits a dominant failure mode of intergranular fracture requiring significant energy for crack propagation. The method of manufacturing is cost-effective by allowing the use of "dirty" raw materials since the process causes impurities to segregate at multi-grain boundary junctions to form isolated pockets of impurities which do not affect the structural integrity of the material. End uses include use as protective projectile-resistant armor.

The present invention relates to a monolithic, fully dense, silicon carbide material, methods of manufacturing the material and end uses. The main use for the present invention consists of use as projectile-resistant armor for mounting on vehicles or other objects and devices which must be resistant to penetration by various projectiles such as, for example, kinetic energy or shaped charged penetrators/projectiles and ballistic fragments.
The following prior art is known to Applicant:
U.S. Pat. No. 3,592,942 to Hauck et al. discloses the use of silicon carbide as an armor material. The present invention differs from the teachings of Hauck et al. as contemplating a particular grain size and structural mode of crack propagation and resistance thereto nowhere taught or suggested by Hauck et al.
U.S. Pat. No. 3,765,300 and 3,796,564 to Taylor et al. teach a dense carbide composite for armor and abrasives. Taylor et al. disclose that ". . . it is essential that the granular boron carbide in the initial mixture have a maximum particle size of about 300 microns or less, although coarser material may be employed to make composite bodies useful for less demanding purposes." Taylor et al. further disclose that "The modulus of rupture may be as low as 10,000 psi (700 kg/cm.sup.2), especially where granular boron carbide with a particle size greater than about 300 microns is included in the mix . . .". As such, Taylor et al. fail to contemplate the grain size disclosed herein nor the method of manufacturing nor the intergranular fracture and resistance thereto disclosed herein.
U.S. Pat. No. 3,793,648 to Dorre et al. discloses a bullet resisting armor including a ceramic layer. This patent is believed to be of only general interest concerning the teachings of the present invention.
U.S. Pat. No. 3,859,892 to Coes discloses a composite ceramic armor including disclosure of the use of ceramic plates made of materials such as "polycrystalline alumina, silicon carbide or boron carbide". This patent is believed to be of only general interest concerning the teachings of the present invention.
U.S. Pat. No. 3,977,294 to Jahn discloses composite armor and method. This patent contemplates a composite laminate material including layers of graphite and ceramic materials adhered together through the use of an adhesive. The ceramic materials disclosed herein are nowhere taught or suggested by Jahn.
U.S. Pat. No. 4,692,418 to Boecker et al. discloses a sintered silicon carbide/carbon composite ceramic body having fine microstructure. This patent discloses making of a silicon carbide material and, thereafter, infiltrating a source of carbon therein to provide the composite body. The present invention differs from the teachings of Boecker et al. as contemplating a monolithic silicon carbide material possessing unique properties and made in a manner not contemplated by Boecker et al.
U.S. Pat. No. 4,693,988 to Boecker et al. discloses a single phase silicon carbide refractory. The Boecker et al. material consists of a pressureless sintered product made from starting materials wherein a coarse fraction as well as a fine fraction are present. Boecker et al. disclose that the coarse fraction has a particle size ranging between 210 and 340 micrometers, huge particles as compared to those contemplated herein. In Boecker et al., all particles are carried through to the final microstructure, that is, they do not reduce in size during the sintering process. Ballistic test results show that such grains incorporated within a SiC microstructure would clearly exhibit transgranular fracture when impacted by a projectile as compared to the present invention wherein intergranular fracture would occur but mechanisms to resist such fracture exist. The inventive grain size (material microstructure) disclosed in this patent application is preferably equal to or less than 7 micrometers which is required to facilitate intergranular fracture. That is, experimentation has revealed that silicon carbide grains larger than 7 micrometers generally exhibit transgranular fracture and grains smaller than 7 micrometers generally exhibit intergranular fracture. As such, the present invention clearly differs from the teachings of Boecker et al.
U.S. Pat. No. 4,813,334 to Bloks et al. discloses armor plates including layers of ceramic material and fiber reinforced plastic separated by metallic plates. This patent is believed to be of only general interest concerning the teachings of the present invention.
U.S. Pat. No. 4,876,941 to Barnes et al. discloses a composite for protection against armor-piercing projectiles. The disclosed material is a ceramic composite comprising titanium boride combined with aluminum nitride. Hot pressing techniques are employed in the manufacture of this material. The present invention differs from the teachings of Barnes et al. as contemplating a monolithic silicon carbide evidencing a mode of failure defined as intergranular in nature. While aluminum nitride is employed in the process of manufacturing the inventive ceramic, it is only used as a densification aid and in proportion much smaller than the proportion of silicon carbide which is employed. In a composite, such as that which is disclosed by Barnes et al., the aluminum nitride is an integral part of the microstructure, that is, aluminum nitride grains are present and can be specifically identified as aluminum nitride. In contrast to this, in the present invention, aluminum nitride behaves as a densification aid. After processing, one may not identify specific aluminum nitride grains. Aluminum nitride is not an integral part of the microstructure and, chemically, the finished ceramic body does not show the presence of aluminum nitride.
K. Nakamura and K. Maeda, in Silicon Carbide Ceramics, Volume 2, Edited by S. Somiya and Y. Inomata, Elsevier Applied Science, 1991, disclose hot-pressed SiC ceramics. These investigators have demonstrated a hot-pressed silicon carbide material using aluminum nitride (AlN) as a processing aid with a Weibull modulus of 13.8. The inventive silicon carbide material disclosed herein contemplates a Weibull modulus within a range of 18 to 30, much higher than Nakamura et al. which makes it possible to produce components with outstanding performance characteristics and exceptional reliability where prior state-of-the-art materials could not be used. The present invention also differs from the teachings of Nakamura et al. as contemplating densification techniques and relation between weight of AlN addition to SiC powder surface area nowhere taught or suggested therein.

Monolithic, fully dense silicon carbide material, method of manufacturing and end uses


A building automation system may control ultraviolet lights to intelligently disinfect susceptible environments based on occupant density. The system comprises multiple occupancy sensors, a disinfection environment tracking engine, and an ultraviolet light control engine. The multiple occupancy sensors generate real time occupancy data associated with multiple objects detected within an area. The disinfection environment tracking engine determines real time occupant density of the multiple objects detected within the area based on the real time occupancy data generated by the multiple occupancy sensors. The ultraviolet light control engine controls operation of one or more ultraviolet lights to disinfect the area based on the real time occupant density determined by the disinfection environment tracking engine.

Building automation systems may be used to control environmental conditions in buildings. The systems provide the capability of managing many building management components from a central front-end interface or group of interfaces. The building management components may include building equipment for lighting, power, heating, ventilation, air conditioning, fire safety, and security. The building automation systems offer operational and sustainability benefits for building developers, managers, and occupants.
Buildings may include environments susceptible to infection or contamination. Healthcare associated infections, in particular, pose a significant issue in modern medical practice. Annual medical costs arising from healthcare associated infections are significant and continue to increase. Mechanisms to address healthcare associated infections include surface cleaning, personal hygiene, and, more recently, ultraviolet (UV) disinfection through UV lighting. Use of UV lights for UV disinfection, in combination with other medical cleaning processes, can result in marked decreases in healthcare associated infections. However, manual operation of UV lights can be cumbersome and inefficient. UV disinfecting lights also pose safety issues, as inadvertent exposure to UV lighting by patients, medical personnel, or other persons may cause significant bodily harm.

Systems and methods for intelligent disinfection of susceptible environments based on occupant density


A sensor system for determining crop yield. The sensor system comprises a mounting structure mounted to a housing of a grain elevator of an agricultural work machine and has at least one aperture formed therein. A fulcrum assembly is arranged on the mounting structure. A rocker arm is pivotal about a pivot axis of the fulcrum assembly and extends between a first end and a second end. An engagement member is coupled to the second end of the rocker arm and extends through the at least one aperture of the mounting structure. At least one gap distance sensor is mounted to the fulcrum assembly and is configured to detect an inclination of the rocker arm relative to the fulcrum assembly. A processing device is coupled to the gap distance sensor and is configured to correlate the detected inclination of the rocker arm to an applied force.

During harvesting, the real-time monitoring and determination of crop yields is often desirable to improve harvesting operations and to provide pertinent information (e.g., crop performance) about the crop being harvested. For example, such information can be used to determine high and low performance areas, as well as for comparison purposes to compare the yield of a variety of seed types. The yield monitor for grain measures and records information such as grain flow, grain moisture, area covered, and location. Based on the measured yield, other properties may be determined such as moisture and grain flow.
Some conventional approaches have employed the use of translational (i.e., non-rotational and linear translation) sensor devices for measuring yields. Translational sensor devices, however, pose significant disadvantages such as decreased sensor resolution, increased measurement errors, and limited sensing ranges, thereby resulting in imprecise yield measurements that can be costly. Other conventional approaches have employed fill level sensors that determines mass flow based on a measured change in a dielectric constant of a parallel plate capacitor. Drawbacks to such conventional approaches include low sensor resolution and decreased sensing accuracy. As such, there is a need in the art for an improved sensor system that overcomes the limitations of the conventional approaches.

Sensor system for determining crop yield


Input MPEG compressed data is input into a partial decoder and a logo insertion controller. A block DCT coefficients (a) output from the partial decoder is divided into a logo insertion region (c) and a non-logo insertion region (d) in a logo insertion region separator. Logo data (e) supplied from a logo information supply section is combined into the logo insertion region (c) with an arbitrary mixing ratio in a logo information insert section. In a logo region partial re-encoder, intra-frame coding of an image insertion region is executed when a starting frame for inserting an image is an intra-coded frame or a predictive coded frame, and, when the starting frame is a bidirectionally predictive-coded frame, inter-frame coding of the image insertion region is executed, and intra encoding of the image insertion region is executed in a frame to which the starting frame for inserting the image can refer.

1. Field of the Invention
The present invention relates to an image insertion device for compressed video data, by which a logo image is inserted into video data with a high speed and high efficiency.
2. Description of the Related Art
As a previous method for inserting an image into compressed video data, there is, for example, an image insertion method at a base band, as shown in FIG. 11. Hereinafter, operations in the previous method will be explained. In the first place, a decoder 101 decodes all data in one frame of MPEG compressed data as an input signal. Then, an image 103 to be inserted is inserted into the decoded image in a combiner 102 to be recompressed in an encoder 104. In this case, coding information (p) of input data which has been decoded in the decoder 101, for example, information such as moving information MV and encoding type is sent to the encoder 104 and is used for encoding. MPEG data after the image was inserted is output from the encoder 104.
Though an image 103 such as an logo image can be inserted into the input video without almost causing image degradation according to the previous method, there has been a very large problem that an entire amount of processing is large and the processing cost is large even if the coding information (p) on input video is used, because encoding is executed again in the encoder 104.
As another previous method for inserting an image, a method by which a logo image is inserted on the compressed data has been disclosed, for example, in the Japanese Patent Application Publication No. 2001-268572. The method comprises: a step for receiving encoded bit-stream; a step for partially decoding the bit stream; a step for inserting a visual element into the bit stream which has been partially decoded; a step for recoding the bit stream into which the visual element has been inserted; and a step for outputting the recoded bit-stream.
Since the encoded bit-stream is partially decoded according to the method, the entire amount of processing can be reduced.
However, when a logo insertion frame is started from a bidirectionally predictive-coded frame (B frame) in the previous method by which the logo image is inserted on the compressed data, there is a possibility that an encoding efficiency is reduced, because both of the logo region and the non-logo region of the starting prediction frame are recoded according to an inter-frame prediction method to cause inter-frame encoding of the logo region with a low inter-frame encoding efficiency. Here, the reason why the inter-frame encoding efficiency of the starting frame is low is that the inter-frame correlation of the logo region is very weak because there is no logo in frames before the starting frame.
Moreover, since encoding is executed without depending on the mixing ratio between the logo image and the original one, there is a possibility that the encoding efficiency for the logo image with a high mixing ratio (for example, when a deep logo image is combined) is reduced when encoding according to the inter-frame prediction is used in a similar manner to that of the original video.
Here, when an intra-coded frame, instead of the bidirectionally predictive-coded frame (B frame) of the starting frame, is used in order to solve the above-described problem, there has been a problem that image degradation is caused since intra encoding which requires a large amount of bits is used, in spite of a state in which a distributed amount of bits for the bidirectionally predictive-coded frame is small, therefore the amount of bits required for intra encoding becomes insufficient.

Image insertion device for compressed video data


A joint prosthesis system is suitable for cementless fixation. The system has two metal implant components and a bearing. One of the metal implant components has an articulation surface for articulation with the bearing. The other metal implant component has a mounting surface for supporting the bearing. One of the metal implant components includes a solid metal portion and a porous metal portion. The porous metal portion has surfaces with different characteristics, such as roughness, to improve bone fixation, ease removal of the implant component in a revision surgery, reduce soft tissue irritation, improve the strength of a sintered bond between the solid and porous metal portions, or reduce or eliminate the possibility of blood traveling through the porous metal portion into the joint space. A method of making the joint prosthesis is also disclosed. The invention may also be applied to discrete porous metal implant components, such as augment.

During the lifetime of a patient, it may be necessary to perform a joint replacement procedure on the patient as a result of, for example, disease or trauma. The joint replacement procedure may involve the use of a prosthesis that is implanted into one or more of the patient's bones. In the case of a knee replacement procedure, a tibial tray is implanted into the patient's tibia. A bearing is then secured to the tibial tray. The condyle surfaces of a replacement femoral component bear against the tibial bearing.
One type of knee prosthesis is a fixed-bearing knee prosthesis. As its name suggests, the bearing of a fixed-bearing knee prosthesis does not move relative to the tibial tray. Fixed-bearing designs are commonly used when the condition of the patient's soft tissue (i.e., knee ligaments) does not allow for the use of a knee prosthesis having a mobile bearing.
In contrast, in a mobile-bearing type of knee prosthesis, the bearing can move relative to the tibial tray. Mobile-bearing knee prostheses include so-called "rotating platform" knee prostheses, wherein the bearing can rotate about a longitudinal axis on the tibial tray.
Tibial trays are commonly made of a biocompatible metal, such as a cobalt chrome alloy or a titanium alloy.
For both fixed and mobile-bearing knee prostheses, the tibial trays may be designed to be cemented into place on the patient's tibia or alternatively may be designed for cementless fixation. Cemented fixation relies on mechanical bonds between the tibial tray and the cement as well as between the cement and the bone. Cementless implants generally have surface features that are conducive to bone ingrowth into the implant component and rely to a substantial part on this bony ingrowth for secondary fixation; primary fixation is achieved through the mechanical fit of the implant and the prepared bone.
Tibial components of both fixed and mobile-bearing and cemented and cementless knee arthroplasty systems are commonly modular components, comprising a tibial tray and a polymeric bearing carried by the tibial tray. The tibial trays commonly include features extending distally, such as pegs or stems. These extensions penetrate below the surface of the tibial plateau and stabilize the tibial tray component against movement. In cementless tibial implants, the outer surfaces of these extensions are typically porous to allow for bone ingrowth. For example, in the Zimmer Trabecular Metal Monoblock tibial trays, pegs with flat distal surfaces and hexagonal axial surfaces are formed completely of a porous metal. In such trays, bone ingrowth is likely to occur along all surfaces of the pegs, including the distal surfaces.
Femoral components of such knee prosthesis systems are also designed for either cemented or cementless fixation. For cemented fixation, the femoral component typically includes recesses or cement pockets. For cementless fixation, the femoral component is designed for primary fixation through a press-fit, and includes porous bone-engaging surfaces suitable for bone ingrowth. Both designs may include pegs designed to extend into prepared holes in the femur for stabilization of the implant.
On occasion, the primary knee prosthesis fails. Failure can result from many causes, including wear, aseptic loosening, osteolysis, ligamentous instability, arthrofibrosis and patellofemoral complications. When the failure is debilitating, revision surgery may be necessary. In a revision, the primary knee prosthesis (or parts of it) is removed and replaced with components of a revision prosthetic system.
When the tibial or femoral implant includes extensions (such as pegs or stems) that extend into the natural bone, a revision surgery usually requires a large resection of the bone in order to dislodge the extensions from the bone. This large resection not only complicates the surgery, it also requires removal of more of the patient's natural bone than is desirable. This removal of additional bone may further compromise the bone, increase the risk of onset of bone pathologies or abnormalities, or reduce the available healthy bone for fixation of the revision implant. Moreover, the large resection usually means that a larger orthopaedic implant is necessary to fill the space and restore the joint component to its expected geometry.
This difficulty in dislodging the primary implant components from the bones is worsened by the fact that bone also grows into the extensions. Severing these connections may be problematic since not all of these areas are easily accessible without resecting large amounts of bone.
In implants such as the Zimmer Trabecular Metal Monoblock tibia tray, some surfaces of the porous metal portion of the tibial tray may remain exposed above the tibial plateau after implantation. These exposed porous metal surfaces may be rough and may irritate the patient's soft tissue as the patient engages in normal day-to-day activities.
Similar issues may be presented in other types of joint prostheses.

Prosthesis with surfaces having different textures and method of making the prosthesis


A piezoelectric actuator includes a piezoelectric vibrating plate including piezoelectric ceramics, an internal electrode formed on a first surface of the piezoelectric vibrating plate, a piezoelectric layer formed on the internal electrode, and a plurality of surface electrodes that are provided on a surface of the piezoelectric layer. When the internal electrode is grounded and a predetermined voltage is applied to a liquid contacting with a second surface of the piezoelectric vibrating plate, a value of a current flowing between the liquid and the internal electrode is not more than 0.01 μA.

Products using piezoelectric ceramics include, for example, a piezoelectric actuator, a filter, a piezoelectric resonator (including an oscillator), an ultrasonic vibrator, an ultrasonic motor, a piezoelectric sensor, and the like. Amongst these products, the piezoelectric actuator has a response speed to an electrical signal of as fast as 10−6 seconds. The piezoelectric actuator is used to position an XY stage of a semiconductor manufacturing apparatus or for a printing head (liquid eject apparatus) of an ink jet printer. Recently, with high speed and low cost being required for a color printer, the demand for an ink eject piezoelectric actuator of an ink jet printer or the like has been increased.
JP-A-2004-165650 discloses a piezoelectric actuator that has a plurality of displacement elements each having a piezoelectric ceramic layer (piezoelectric layer) and a pair of electrodes with the piezoelectric layer interposed therebetween. The piezoelectric layer is disposed on a surface of a ceramic substrate. A piezoelectric vibrating plate formed of a piezoelectric material (piezoelectric ceramics) is used as the ceramic substrate, and the piezoelectric actuator is used for a printing head (liquid eject apparatus).
FIG. 5 is a schematic cross-sectional view showing a known liquid eject apparatus having a piezoelectric actuator disclosed in JP-A-2004-165650. As shown in FIG. 5, the liquid eject apparatus 70 has a plurality of liquid flow passages 53a arranged in parallel. The liquid eject apparatus 70 also has a piezoelectric actuator 61 provided on a flow passage member 53 which forms partition walls 53b serving as walls partitioning the individual liquid flow passages 53a.
The piezoelectric actuator 61 has a plurality of displacement elements 67 provided on a surface of a piezoelectric vibrating plate 62. Each of the displacement elements 67 has a piezoelectric layer 65 and a pair of electrodes (an internal electrode 64 and a surface electrode 66) with the piezoelectric layer 65 interposed therebetween. The piezoelectric actuator 61 is mounted on the flow passage member 53 such that the positions of the liquid flow passage 53a and the surface electrode 66 are aligned with each other.
A common liquid supply flow passage (not shown), which is provided in the flow passage member 53, is connected to each of the liquid flow passages 53a. The liquid from the outside is supplied to and filled into each of the liquid flow passages 53a from the liquid supply flow passage. If the liquid is ejected, the ejected liquid flows into each of the flow passages 53a through the supply flow passage. For this reason, the rear surface of the piezoelectric vibrating plate 62, which is located above each of the liquid flow passages 53a, is brought into contact with the liquid flowing in the liquid flow passage 53a.
The liquid eject apparatus 70 displaces a displacement element 67 by applying the driving voltage between the surface electrode 66 and the internal electrode 64 so as to change a volume of the liquid flow passage 53a. Accordingly, the liquid in the flow passage 53a is pressurized and the liquid is ejected from the liquid eject port 58 that is opened at the bottom of the flow passage member 53.
However, if a predetermined driving voltage is repeatedly applied for a long time in a state where the piezoelectric vibrating plate 62 is brought into contact with the liquid, the internal electrode 64 and the piezoelectric vibrating plate 62 are separated from each other. Thus, driving durability is lowered. This problem drastically appears in a piezoelectric actuator having a thickness of not more than 100 μm.

Piezoelectric actuator, inspection method, and liquid eject apparatus


The present invention aims to provide an adhesive composition showing high adhesion and cohesion as well as good heat resistance. Adhesive compositions of the present invention include an imide (meth)acrylate, a monomer having a glass transition temperature of xe2x88x9250xc2x0 C. or less when it is homopolymerized, and a photoinitiator, wherein the content of the imide (meth)acrylate is 1-20 parts by weight per 100 parts by weight of the monomer.

The present invention relates to adhesive compositions showing adhesive properties upon irradiation (with UV rays, for example) and adhesive sheets prepared therefrom.
Generally, one-pack solvent-free acrylic adhesive compositions that contain monomer as polymerization component and initiator, comprise a hard segment component showing a relatively high glass transition temperature (Tg) (e.g., about 60 to 180xc2x0 C.) and conferring high cohesion on adhesives (such as acrylic acid, methyl methacrylate, etc.), a soft segment component showing a relatively low glass transition temperature (eg, about xe2x88x9290 to xe2x88x9220xc2x0 C.) and conferring high adhesion on adhesives (such as butyl acrylate (Tg=xe2x88x9254 xc2x0 C.), 2-ethylhexyl acrylate (Tg=xe2x88x9285xc2x0 C.), etc.), a component showing an intermediate glass transition temperature (e.g., about xe2x88x9220 to 60xc2x0 C.) (such as t-butyl acrylate (Tg=41xc2x0 C.), vinyl acetate, etc.), and a photoinitiator. The acrylic adhesive composition is cured by irradiation to show adhesive properties (JPA No. 2000-073025, etc.).
However, adhesive compositions such as those described above have the disadvantage that, when the content of the soft segment component is increased to further improve adhesion, the content of the hard segment component relatively decreases to lower cohesion and on the contrary, when the content of the hard segment component is increased to further improve cohesion, the content of the soft segment component relatively decreases to lower adhesion. Thus, no adhesive compositions achieving high adhesion and high cohesion at the same time have been obtained.
One important application of solvent-free acrylic adhesive compositions is the use as adhesives for bonding a backing film to a flexible circuit board. However, conventional solvent-free acrylic adhesive compositions are insufficient in heat resistance against the lead-free solder technique that has recently come to be used in this field of application and has a melting point 30 to 40xc2x0 C. higher than that of traditional solder, and tackiness of adhesives is impaired during the solder reflow processes.
What is needed, therefore, is an adhesive composition that shows high adhesion and cohesion as well as good heat resistance.
In one aspect, the present invention relates to adhesive compositions containing a major component monomer having a glass transition temperature of xe2x88x9250xc2x0 C. or less when it is homopolymerized and an imide (meth)acrylate in a specific ratio that show high adhesion and high cohesion at the same time while maintaining heat resistance.
Accordingly, in one aspect the present invention provides an adhesive composition comprising an imide (meth)acrylate, a homopolymerizable monomer having a glass transition temperature of xe2x88x9250xc2x0 C. or less when it is homopolymerized, and a photoinitiator, wherein the content of the imide (meth)acrylate is 1 to 20 parts by weight per 100 parts by weight of the monomer.
In another aspect, the present invention provides an adhesive composition wherein the imide (meth)acrylate is 2-(perhydrophthalimide-N-yl)ethyl acrylate.
In another aspect, the present invention comprises an adhesive composition that includes 1 to 5 parts by weight of a compound per 100 parts by weight of the homopolymerizable monomer, and the compound is copolymerizable with the homopolymerizable monomer.
In one aspect, the present invention comprises an adhesive composition wherein the compound that is copolymerizable with homoplymerizalbe monomer includes at least one member selected from the group of acrylic acid, isobomyl acrylate and morpholine acrylate.
In one aspect, the present invention also provides an adhesive sheet comprising an adhesive layer where the adhesive layer is formed by curing an adhesive composition. The adhesive composition includes imide (meth)acrylate and homopolymerizable polymer and photoinitiator, wherein a glass transition temperature of the homopolymerizable monomer is xe2x88x9250xc2x0 C. or less when it is homopolymerized, and the content of the imide (meth) acrylate is 1 to 20 parts by weight per 100 parts by weight of the monomer.

Adhesive compositions and adhesive sheets


A bypass system is provided for a long cement kiln. The long cement kiln includes a cylindrical rotary vessel in which a kiln gas stream flows countercurrent to in-process mineral. The bypass system includes an annular bypass plenum, a port in the wall of the rotary vessel in gas flow communication with said plenum, and a draft tube for preventing passage of in-process mineral through said port. A blower fan induces flow of at least a portion of the kiln gas stream to form a bypass stream through the draft tube and the port and into the annular bypass plenum. The bypass system also includes an apparatus for mixing controlled amounts of ambient air with the bypass stream to cool the kiln gas bypass stream and to precipitate alkali fume in the kiln gas bypass stream before it passes through the draft tube and the port in the wall of the rotary vessel to reduce build up of condensed alkali inside the draft tube.

This invention relates to improvements in the operation and configuration of long rotary cement kilns. More particularly it is directed to a method and apparatus for enhancing the capacity and efficiency of cement clinker production in conventional wet or dry process long rotary kilns. A portion of the kiln gases is withdrawn from the rotary vessel at a point upstream, relative to kiln gas flow, of the mineral drying zone and pre-heating zone to form a kiln gas bypass stream.
In the widely used commercial process for the manufacture of cement, the steps of drying, calcining, and clinkering cement raw materials are accomplished by passing finely divided raw materials, including calcareous minerals, silica and alumina, through a heated, inclined rotary vessel or kiln. In what is known as conventional long dry or wet process kilns the entire mineral heating process is conducted in a heated rotating kiln cylinder, commonly referred to as a "rotary vessel." The rotary vessel is typically 12 to 15 feet in diameter and 400-700 feet in length and is inclined so that as the vessel is rotated, raw materials fed into the upper end of the kiln cylinder move under the influence of gravity toward the lower "fired" end where the final clinkering process takes place and where the product cement clinker is discharged for cooling and subsequent processing. Gas temperatures in the fired clinkering zone of the kiln range from about 1300.degree. to about 1600.degree. C. Kiln gas temperatures are as low as about 250.degree. to 350.degree. C. at the upper mineral receiving end of so-called wet process kilns. Somewhat higher gas temperatures exist in the upper end of long dry process kilns.
Generally, skilled practitioners consider the cement making process within the rotary kiln to occur in several stages as the raw material flows from the cooler gas exit mineral feed end to the fired/clinker exit lower end of the rotary kiln vessel. As the mineral material moves down the length of the kiln it is subjected to increasing kiln gas temperatures. Thus in the upper portion of the kiln cylinder where the kiln gas temperatures are the lowest, the in-process mineral materials first undergo a drying process and thereafter move into the hotter calcining zone and finally into the portion of the kiln where the kiln gas temperatures are the hottest, the clinkering zone adjacent to the fired lower end of the kiln cylinder. The kiln gas stream flows counter to the flow of in-process mineral materials from the clinkering zone, through the intermediate calcining zone and the mineral drying zone and out the upper gas exit end of the kiln into the kiln dust collection system. The flow of kiln gases through the kiln can be controlled to some extent by a draft induction fan positioned in the kiln gas exhaust stream.
The drying/pre-heat zone of a long process kiln is defined as that part of the kiln in which sufficient heat transfer takes place from the kiln gas stream to the mineral bed to eliminate moisture from the mineral raw material feed. In the drying zone, the mineral material is heated to a temperature of up to approximately 1500.degree. F., the temperature at which mineral carbonates begin to calcine (release carbon dioxide). To facilitate the transfer of heat in the drying/pre-heat zone, chain curtains are provided. As mineral material is introduced and travels down the length of the drying zone, the chains continually rotate between the hot kiln gas phase and the mineral material phase transferring heat from the gases to the raw materials.
One of the shortcomings of the use of conventional long kilns for cement manufacture derives from the significant quantities of dust generated in the drying zone of the kiln and carried out of the kiln in the kiln gas stream. On the average about 7-10% (but as high as about 17%) of the raw material feed on a dry basis is blown back from the drying zone as dust. The high dust loss associated with the manufacture of cement clinker in long wet or dry process kilns places long kiln operators at a significant economic disadvantage relative to cement manufacturers using the newer pre-heater/pre-calciner kilns. High dust loss not only means loss of efficiency of use of raw materials--dust recovery is limited because of contamination by volatile alkali salts--but it also requires greater capital investment in dust collection equipment and loss of energy efficiency. Every ton of raw material lost as dust consumes significant amounts of heat energy during drying. Further the long kiln operator is burden by the cost of handling/disposal of waste dust.
Another disadvantage suffered by cement manufacture in conventional long kilns relative to that in pre-heater/pre-calciner kilns derives from the internal cycling of volatile alkali salts. As the in-process mineral travels down the kiln to the hotter zones, alkali salts such as potassium and sodium sulfates in the mineral are volatilized into the kiln gas stream and carried as an alkali fume into the coolest zones of the kiln, including particularly the dust generating drying zone where the alkali fume condenses on the dust and either falls back into the in-process mineral bed or is carried out of the kiln in the kiln gas stream and collected with the kiln dust in the dust collection system. It is the presence of the significant quantities of condensed alkali salts in the kiln dust that prohibits the return of the dust to the process--adding the alkaline dust to the mineral raw material can disrupt the alkali salt recirculation equilibrium and cause unacceptably high alkalinity in the cement product.
During cement kiln operation there is significant recirculation of alkali salts from the mineral bed to the kiln gas stream and back to the mineral bed. At equilibrium conditions where the alkali salts are carried out of the kiln at the same rate at which they are introduced in fuels and raw materials, it is estimated that there is 90% trapping of the volatilized alkali. The internal cycling of high quantities of alkali salts during kiln operation constitutes a significant energy burden on the process. Large quantities of high grade heat in the hotter zones of the kiln (where the heat is needed most) are lost to alkali volatilization only to be returned to the process as low grade heat during condensation in the lower temperature zones where excess heat is not needed. The configuration of pre-heater/pre-calciner kilns allows facile installation of alkali bypass conduits through which a portion of the alkali fume-laden kiln gas stream can be withdrawn before it becomes contaminated with entrained kiln dust, thereby not only reducing the alkali load in the internal cycle, but also providing means for recovery of a product highly enriched in the volatile alkaline salts. Until recently, there has been no means for establishing an alkali bypass for conventional long wet or dry process kilns.
There are many existing long kiln cement manufacturing operations, not only in the United States but in many other countries as well around the world. A method/apparatus for reducing dust loss and for enhancing control of the internal alkali cycling in long kiln cement manufacturing operations is disclosed in copending U.S. patent application Ser. No. 07/913,587, now abandoned, which is incorporated herein by reference. The invention disclosed in the '587 application enables long kiln operators to be more economically competitive with pre-heater/pre-calciner kiln operators.
The '587 application discloses modifying the kiln to allow withdrawal of a portion of the kiln gases from the rotary vessel at a point upstream, relative to kiln gas flow, of the mineral drying zone. By removing a portion of the kiln gas from the calcining zone, or more particularly from a point upstream, relative to kiln gas flow, of the mineral drying zone (most particularly the chain curtain section) and downstream of the hottest portions of the calcining zone, there is achieved a substantial reduction in dust generated and lost from the drying zone. Reduced dust loss derives not only from reduced kiln gas velocities in the drying zone, but also from the resultant extension of the drying zone itself. Removing a portion of the hot kiln gas stream results in an extended drying zone--the raw feed will have a greater moisture content through the chain curtain section of the kiln, effectively reducing the generation of dust in the drying zone.
Preferably the bypass is designed to withdraw at least about 10% of the hot kiln gases at a point upstream of the mineral drying/pre-heat zone. The bypass gases are cooled, for example, by mixing with ambient air and either returned to the kiln gas stream upstream of the kiln dust collection system, including for example, an electrostatic precipitator, or directed to an independent dust collection system.
A 10% reduction of kiln gas flowing through the drying zone is expected to result in an average velocity reduction in the drying zone of about 20% by the combined action of reduced mass and temperature. With that velocity reduction, the amount of dust blown by the gas stream out the upper gas exit end of the kiln will decrease significantly. The reduced dust loss allows an associated reduction in the amount of raw material for the same amount of clinker production. Of course, reduced dust loss also means less dust requiring disposal by the kiln operator and less of a dust load on the dust collection system.
A shortcoming associated with the bypass system disclosed in the '587 is that condensed alkali tends to build up inside bypass inlet tube as the kiln gas cools in the inlet tub. An air cannon is used periodically during kiln operation to clear condensed alkali from the port and the bypass inlet tube during kiln operation without perturbation of the on-going cement manufacturing process. An industrial 8-gauge shotgun utilizing No. 4 zinc shot can be substituted for air cannon or used in combination therewith to clear condensed alkali from port and bypass inlet tube.
An object of the present invention is to reduce or prevent buildup of condensed alkali inside a bypass inlet tube of a long kiln bypass system.
According to one aspect of the present invention, an improved design for bypass apparatus is provided for use with a long cement kiln. The long cement kiln comprises a cylindrical rotary vessel in which a kiln gas stream flows countercurrent to in-process mineral. The bypass apparatus comprises an annular bypass plenum, a port in the wall of the rotary vessel in gas flow communication with said plenum, means for preventing passage of in-process mineral through said port, and means for inducing flow of at least a portion of the kiln gas stream to form a bypass stream through said port and into the annular bypass plenum. The improvement of the present invention comprises means for mixing controlled amounts of ambient air with said bypass stream before it passes through said port in the wall of the rotary vessel.
The means for preventing passage of in-process mineral through the port includes a draft tube having a first end communicating with the port and a second end communicating with the kiln gas stream. The means for mixing ambient air with the bypass stream includes means for delivering ambient air to the second end of the draft tube. The ambient air delivery means includes an air conduit for directing ambient air to the second end of the draft tube and means for controlling ambient air flow through said conduit.
The air conduit is in gas flow communication with at least a portion of an annular space defined by the outer surface of the rotary vessel and a sealing sleeve mounted on the rotary vessel in axial alignment with the port. The portion of the annular space in gas flow communication with the air conduit is further in gas flow communication with a windbox comprising an annular plenum and the means for controlling air flow into the air conduit includes a variable speed fan in air flow communication with the annular plenum of the windbox.
In the illustrated embodiment, the air conduit for directing ambient air to the second end of the draft tube comprises an annular channel defined by the draft tube and a draft tube sleeve surrounding the draft tube. The draft tube sleeve extends into the rotary vessel beyond the second end of the draft tube. The draft tube sleeve includes a radially inwardly extending flange having an upturned lip for deflecting ambient air toward the second end of the draft tube.
According to another aspect of the present invention, a method is provided for enhancing the capacity and efficiency of clinker production of an operating conventional wet or dry long rotary kiln. The kiln comprises a rotary vessel having a fired lower end and an adjacent clinkering zone, an upper gas exit end and an adjacent mineral drying zone, and an intermediate calcining zone along its length and a kiln gas stream flowing from the clinkering zone through the intermediate calcining zone and mineral drying zone out the gas exit end to a kiln dust collection system. The method comprises the steps of withdrawing a portion of the kiln gases through a port formed in a wall of the rotary vessel at a point upstream, relative to kiln gas flow, of the mineral drying zone to form a kiln gas bypass stream, and mixing controlled amounts of ambient air with said kiln gas bypass stream to cool the kiln gas bypass stream and to precipitate alkali fume in the bypass stream before it passes through the port in the wall of the rotary vessel.
The method further includes the step of further cooling or quenching the gas bypass stream after the gas bypass stream passes through the port in the wall of the rotary vessel to cool said gas bypass stream to a predetermined operating temperature. The bypass stream is preferably further cooled (quenched) by its mixture with ambient air optionally in combination with a water spray after the kiln gas bypass stream passes through the port in the wall of the rotary vessel. The illustrated method further includes the steps of collecting at least a portion of precipitated alkali fume from the cooled gas bypass stream and recombining the quenched kiln gas bypass stream with the kiln gases upstream, relative to kiln gas flow, of the kiln dust collection system.
According to yet another aspect of the present invention, an apparatus is provided for enhancing the capacity and efficiency of clinker production of a conventional wet or dry long rotary kiln. The kiln comprises a rotating vessel having a fired lower end and an adjacent clinkering zone, an upper kiln gas exit end and an adjacent mineral drying zone, and an intermediate calcining zone along its length and a kiln gas stream flowing from the clinkering zone through the intermediate calcining zone and upper mineral drying zone to a kiln dust collection system. The apparatus includes a port formed in the rotary vessel at a point upstream, relative to kiln gas flow, of the mineral drying zone. The apparatus also includes a draft tube for preventing passage of in-process mineral through the port. The draft tube has a first end communicating with the port and a second end communicating with the kiln gas stream. The apparatus further includes an annular plenum in alignment with the port axially along the length of the rotary vessel, in gas flow communication with said port and having located thereon an air inlet damper valve. The apparatus still further includes means for creating reduced pressure in said annular plenum to draw air into said air inlet and to withdraw at least a portion of the kiln gas stream through the draft tube to form a kiln gas bypass stream which passes into said annular plenum. In addition, the apparatus includes means for mixing controlled amounts of ambient air with said the kiln gas bypass stream before it enters the second end of the draft tube to cool the kiln gas bypass stream ant to precipitate alkali fume in the kiln gas bypass stream before it enters the second end of the draft tube to reduce build up of condensed alkali inside the draft tube.
According to a further aspect of the invention, an apparatus is provided for enhancing the capacity and efficiency of clinker production of a conventional wet or dry long rotary kiln. The kiln in operation comprises a rotary vessel having a fired lower end and an adjacent clinkering zone, an upper kiln gas exit end and an adjacent mineral drying zone, and an intermediate mineral calcining zone along its length and a kiln gas stream flowing from the clinkering zone through the intermediate calcining zone and upper mineral drying zone to a kiln dust collection system. The apparatus includes a solid fuel charging port and a gas bypass port formed in the rotary vessel. The fuel charging port is located at a point along the length of the vessel wherein fuel charged through the port will enter the calcining zone. The bypass port is located at a point on the vessel downstream, relative to kiln gas flow, from said fuel charging port. The apparatus also includes means for preventing in-process mineral from passing through each of said fuel charging and bypass ports, and an annular plenum in alignment with the bypass port axially along the length of the rotary vessel and in gas flow communication with said bypass port. The apparatus further includes means for creating reduced pressure in said annular plenum to withdraw at least a portion of the kiln gas stream through the bypass port and into said annular plenum to form a kiln gas bypass stream, and means cooperating with the charging port for charging solid fuel into the calcining zone. The apparatus still further includes means for mixing controlled amounts of ambient air with said bypass stream to quench the kiln gas stream to precipitate alkali fume in the bypass stream before it passes through the bypass port in the wall of the rotary vessel.
According to a still further aspect of the invention, an apparatus is provided for enhancing the capacity and efficiency of clinker production of a conventional wet or dry long rotary kiln. The kiln comprises a rotating vessel having a fired lower end and an adjacent clinkering zone, an upper kiln gas exit end and an adjacent mineral drying zone, and an intermediate calcining zone along its length and a kiln gas stream flowing from the clinkering zone through the intermediate calcining zone and upper mineral drying zone to a kiln dust collection system. The apparatus of the present invention includes a port formed in a wall of the rotary vessel. The port is located axially between the calcining zone and the mineral drying zone. The apparatus also includes a sealing sleeve mounted on the rotary vessel in axial alignment with the port. The sealing sleeve defines an annular space between an outer surface of the rotary vessel and the sealing sleeve. The sealing sleeve is formed to include an aperture therein. A draft tube has a first end which is coupled to the aperture formed in the sealing sleeve. The draft tube extends through the port and into the rotary vessel a predetermined distance which is longer than the maximum depth of in-process mineral in the rotary vessel. The draft tube has a second end in communication with the kiln gas stream. A first annular plenum is located in axial alignment with the port and the aperture in the sealing sleeve. The first annular plenum is in gas flow communication with the port and the aperture in the sealing sleeve. A blower fan is coupled to the first annular plenum for creating reduced pressure in the first annular plenum to withdraw at least a portion of the kiln gas stream through the draft tube and into the first annular plenum to form a kiln gas bypass stream. The apparatus further includes a draft tube sleeve having a first end coupled to the port in the rotary vessel. The draft tube sleeve extends into the rotary vessel and surrounds the draft tube to define an annular channel therebetween for directing ambient air to the second end of the draft tube. The apparatus still further includes a windbox having a second annular plenum in gas flow communication with the annular space between the outer surface of the rotary vessel and the sealing sleeve. In addition, the apparatus includes means for controlling ambient air flow through the second annular plenum, through the annular space between the outer surface of the rotary vessel, and through the annular channel between the draft tube sleeve and the draft tube to mix controlled amounts of ambient air with said kiln gas bypass stream before it enters the second end of the draft tube to cool the kiln gas bypass stream and to precipitate alkali fume in the kiln gas bypass stream before it enters the draft tube to reduce build up of condensed alkali inside the draft tube.
Use of the present bypass apparatus of the present invention in long kilns provides multiple advantages to the cement manufacturing process. The operation of the present bypass system will allow the drying zone of the kiln to operate somewhat independently of the rest of the process. The energy demands of the calcining process are such that more than sufficient energy remains at the process boundary between the calcining and drying/pre-heating zones to accomplish the drying/pre-heating step. By rerouting a portion of the kiln gas around the drying/pre-heating zone through the bypass duct, the amount of energy supplied to the drying/pre-heating zone will more closely match the process requirements of this zone. Consequently, the volume of gases passing through this zone will be reduced, thereby resulting in lower gas velocity. The lower velocity will in turn reduce the amount of in-process material that will be entrained in the kiln gas stream and exit the kiln as cement kiln dust. The reduced velocity of the gas stream in the drying zone during operation of the bypass system results in a 40-75% reduction of kiln dust lost from the kiln, thereby resulting in increased process economy.
Pieces of chain are suspended in the drying/pre-heating zone as an internal heat exchange device. The suspended chains also trap some of the volatile salts (e.g., K.sub.2 SO.sub.4) in the process until equilibrium is reached and an internal cycle of volatile constituents is established in which these constituents leave the process at the same rate at which they are introduced in fuels and raw materials. An internal cycle of alkali salts can cause operating problems such as the buildup of material rings in the kiln. By rerouting a portion of the hot kiln gas containing the gaseous volatile constituents around the chain system, the magnitude of the internal cycle will be reduced, thus improving kiln operation. During operation of the bypass, "bypass gas" will be extracted prior to the gas entering the turbulence of the chain system. As a result, it is expected that there will be little suspended particulate matter in this bypass gas; however, the hot bypass gas will contain the alkali fume and other volatilized components--one target of the bypass arrangement. When the bypass gas stream is recombined with the exit gas from the drying/pre-heating zone of the kiln prior to its entry into the air pollution control (dust collection) system, the thermal energy in the bypass gas ensures that the temperature of the gas is above the dew point even if the kiln exit gas itself is at or below the dew point.
Under 40 C.F.R. 266.104(g), monitoring of CO and THC in a bypass duct is allowed as a means of complying with CO and THC limits, provided that: (1) hazardous waste is fired only into the kiln and not at any location downstream from the kiln exit relative to the direction of gas flow (i.e., downstream from the bypass); and (2) the bypass diverts a minimum of 10% of the kiln off-gas into the duct. The preamble to the BIF regulation (56 F.R. 7159, Feb. 21, 1991) acknowledges that a rationale for allowing monitoring in a bypass duct is that a bypass would preclude the interference of non-fuel THC emissions from raw materials. In long kilns, the raw material is heated in the drying/pre-heating zone to a temperature sufficient to evaporate the hydrocarbons contained therein. The hydrocarbons from that heating process are contained in the kiln exit gases. The bypass duct will draw gas from the kiln prior to its entry into the drying/pre-heating zone; therefore, gases will not have been affected by the raw material heating process. Thus, the monitoring of the bypass gases is a true representation of the gases from the combustion process without interference from hydrocarbons in the raw material.
The present invention also enables enhanced clinker production capacity in long kilns. There are two limiting factors in the production of cement in long wet process kilns: (1) the kiln gas velocity in the drying zone causing dust loss; and (2) thermal loading in the sintering zone. Inherently these factors work to limit the amount of heat energy that can be delivered into the kiln for transfer for the in-process mineral. The impact of the first of those limiting factors can be minimized by use of the present bypass apparatus. Subject to the limitations imposed by factor (2) above, the bypass apparatus can be used to reduce kiln gas stream velocities in the drying zone even with significantly higher energy input into the process.
It has recently been reported in the art that conventional long kilns can be modified to provide an environmentally safe and economically advantageous use of solid waste fuels. Apparatus and methods for delivering solid fuels, especially solid waste fuels, are known in the art. See, for example, U.S. Pat. Nos. 4,930,965, 4,969,407, 4,850,290, 5,078,594 and 5,083,516. The delivery of solid fuel into the calcining zone in accordance with the teachings of those patents tends to increase the temperature of the kiln gas stream, and concomitantly kiln gas stream velocity, through the drying zone with potential enhanced dust loss. The present long kiln bypass method and apparatus can be utilized in conjunction with use of the art-recognized methods and apparatus for burning combustible solids, particularly combustible waste solids, as supplemental fuel in long kilns.
Additional features and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiments exemplifying the best mode of carrying out the invention.

Method and apparatus for improved manufacture of cement in long kilns


A numerical control system controls a plurality of axes with a plurality of channels (10, 20, 30). When a machining program for a first channel (10) is interrupted after a single block in response to a single block signal (6), the feeding of commands of a machining program for other channels (20, 30) is held. The machining programs are thereby executed in synchronism with each other. The machining processes are prevented from being unbalanced, and machining interference is avoided.

There have widely been used numerical control systems for controlling a number of axes or spindles with a plurality of channels (functional arrangements). Such numerical control systems include a numerical control system for controlling a four-axis at he having two spindles and two tool rests. A workpiece can be machined at a high speed by the spindles or tool rests. With the multiple-channel numerical control system, when a single block signal is on, the machining program for a channel is interrupted after a single block, the execution of which is first finished, and the machining program for another channel is executed.
Therefore, the execution of the machining program for one channel is stopped, and the execution of the machining program for another channel is continued. As a result, the machining programs for the channels are not synchronized, the workpiece is machined out of balance, and a machining interference occurs.