A method for enabling control in a cloud computing environment includes initializing a portion of computing resources identified for enabling service to a user system in a cloud computing environment. The method may also include enabling service to the user system. Further, the method may include initializing another portion of the computing resources. After the service in the cloud computing environment has been enabled, cloud computing services may be provided by the host system to one or more user systems.

1. Field of the Invention
The present invention relates to cloud computing, and more specifically, to methods and systems for enabling control to a hypervisor in a cloud computing environment.
2. Description of Related Art
Cloud computing is Internet-based computing, whereby shared resources, software, and information are provided to computers and other devices on-demand, like the electricity grid. Cloud computing describes a new supplement, consumption, and delivery model for Information Technology (IT) services based on the Internet, and it typically involves over-the-Internet provision of dynamically scalable and often virtualized resources to user systems as a service over the Internet. Most cloud computing infrastructure consists of reliable services delivered through data centers and built on servers.
A hypervisor, also referred to as a Virtual Machine Monitor (VMM), allows multiple operating systems to run concurrently on a host system, such as a host computer or server providing cloud computing services to host systems. Such a feature is often referred to as hardware virtualization. The hypervisor may present guest operating systems with a virtual platform and may monitor the execution of the guest operating systems. In this way, multiple operating systems, including multiple instances of the same operating system, can share hardware resources in the cloud computing environment.
Hypervisors are generally classified as being either Type 1 or Type 2. A Type 1 hypervisor (or native, bare metal hypervisor) runs directly on the host's hardware for controlling the hardware and for monitoring guest operating systems. A guest operating system thus runs on another level above the hypervisor. A Type 2 hypervisor (or hosted hypervisor) runs within a conventional operating system environment, with the hypervisor layer as a distinct second software level, and the guest operating systems running at another level above the hardware.
Servers can be over-featured for the fundamental needs of a cloud computing service provider. For example, current cloud computing servers include a firmware abstraction layer such as a basic input/output system (BIOS) layer, a unified extensible firmware interface (UEFI) layer, or an Open Firmware layer. The support of these layers and other firmware can be costly to a server vendor in terms of time and expense.
Accordingly, for at least the aforementioned reasons, there is a desire to reduce the complexity of host systems providing services to user systems in a cloud computing environment.

Methods and systems for enabling control to a hypervisor in a cloud computing environment

International Business Machines Corporation


A POC recalculation value is retrieved by a decoder from an encoded representation of a RAP picture in a base layer of a video stream comprising pictures in multiple layers. POC values of reference pictures in a DPB of the decoder are recalculated using the POC recalculation value. By signaling the POC recalculation value in the RAP picture, which enables the decoder to correctly handle video streams with non-aligned RAP pictures.

The High Efficiency Video Coding (HEVC) video coding standard [1] is currently in the process of being extended to support scalable layers. The plans include spatial, quality, and multiview scalable extensions in which bitstreams contain a base layer and a variable number of enhancement layers. The most recent draft version of the HEVC scalable extension was JCTVC-N1008_v3 [2].
The base layer in a scalable stream complies with the first version of HEVC which does not include any scalable extensions. The enhancement layers in the scalable stream are marked as extension data using types that were defined as reserved in the first version of HEVC. In the HEVC specification the type is indicated using high level signaling and is carried in the Network Abstraction Layer (NAL) unit type. It was in the first version specified that first version decoders, i.e. decoders compliant with the first version of HEVC, will discard data marked with extension types. This enables legacy or first version decoders to correctly decode the base layer in scalable bitstreams while ignoring the enhancement layers. Decoders compliant to an extension of HEVC will recognize the extension data types and be able to also decode the enhancement layers in the scalable bitstream.
Example picture structures using scalability are often illustrated as shown in FIG. 1. The figure illustrates spatial scalability with a lower resolution base layer 10 with three pictures 14, 16, 18 and a higher resolution enhancement layer with three pictures 24, 26, 28. The arrows in the figure show how the pictures reference each other. As you can see, the enhancement layer pictures 24, 26, 28 use the base layer pictures 14, 16, 18 for reference. Since no enhancement layer picture 24, 26, 28 is used for reference by a base layer picture 14, 16, 18, the enhancement layer 20 can be removed, which would result in a first version bitstream (version one bitstream) that would be decodable by a first version decoder (version one decoder). FIG. 1 contains three time instances, for which there are two pictures 14, 24; 16, 26; 18, 28 each, one base layer picture and one enhancement layer picture. These pictures 14, 24; 16, 26; 18, 28 are grouped and called access units (AUs) 30. There are three access units 30 in FIG. 1, of which one is marked with reference signs in order to simplify the figure.
The first version of HEVC is actually somewhat scalable as well since it includes temporal layers. This is illustrated in FIG. 2, which shows three pictures 14, 16, 18 in temporal layer 0 (pictures 2, 4, and 6) 10 and two pictures 24, 26 in temporal layer 1 (pictures 3 and 5) 20. Similar to the spatial scalability example, temporal layer 1 20 can be discarded. In this example the result is a bitstream with half the frame rate. There are five access units 30 in FIG. 2, of which one is marked with reference sign.
A bitstream in which one or more higher layers have been removed is called a subbitstream, regardless whether the higher layer is a temporal layer or a regular layer.
An important rule in HEVC regarding all types of scalability is that no picture of a lower layer is allowed to use a picture of a higher layer for reference. This rule is important as it preserves decodeability for bitstreams in which higher layers have been removed. Another important rule is that if an encoder outputs a scalable bitstream, the encoder is responsible that every possible subbitstream is a compliant bitstream. This means that a network node or any other entity can blindly discard any higher layer combination from a scalable bitstream and be assured that the output is a compliant bitstream. This rule is generally denoted the compliance rule.
Every picture in HEVC has a picture order count (POC) value assigned to it. This value defines the order in which pictures are output; pictures are always output in increasing POC order. Output of pictures from a decoded picture buffer (DPB) is typically output for display on a screen. However, output as used herein also encompass output for other purposes than display including, but not limited to, output for storage on a memory, output for transcoding, etc.
The range of allowed POC values is from −231 to 231−1, so in order to save bits in the slice header, only the least significant bits (LSB) of the POC (POC lsb) are signaled. This is done by the slice_pic_order_cnt_lsb codeword in HEVC. The number of bits to use for POC lsb is signaled in the sequence parameter set (SPS) using the codeword log 2_max_pic_order_cnt_lsb_minus4 and can be between 4 and 16. Since only the POC lsb is signaled in the slice header, the most significant bits (MSB) of the POC (POC msb) for the current picture are derived from the POC of previous pictures and the POC lsb of the current picture. HEVC defines the derivation of the most significant POC bits in equation 8-1 in section 8.3.1 of the HEVC standard [1].
The HEVC standard specifies a number of picture types that have different characteristics. An important set of picture types are the Intra random access point (IRAP) picture types. Those are intra coded pictures that provide random access points in a bitstream.
IRAP pictures in a scalable bitstream can either be aligned or non-aligned. This can be signaled in JCTVC-N1008_v3 [2] using the video parameter set (VPS) codeword cross_layer_irap_aligned_flag, see section F.220.127.116.11.1 in [2]. If this flag is 1 and one of the pictures in an access unit is an IRAP picture, all pictures in that access unit must be IRAP pictures of the same IRAP type. If cross_layer_irap_aligned_flag is set to 0 in the VPS, IRAP pictures are not required to be aligned and the picture structure shown in FIG. 3 is allowed.
An IRAP picture in the base layer provides a point where it is possible to start decoding. An IRAP picture in an enhancement layer provides a point where it is possible to start decoding that layer given that the layer(s) below is(are) being decoded. If IRAP pictures are aligned, the access unit containing IRAP pictures in all layers provide a point where it is possible to start decoding any number of layers.
If IRAP pictures are non-aligned, such as the pictures in FIG. 3, the process from making a random access in the base layer until a certain number of enhancement layers are being decoded is called the layer-wise startup process. The process can be summarized like this:    1 Before decoding, no layer is considered initialized.    2 When an IRAP picture is encountered in a base layer, that layer is immediately considered initialized.    3 When an IRAP picture is encountered in an enhancement layer, that layer is considered initialized if all layers that the enhancement layer is dependent on are initialized.    4 When a non-IRAP picture is encountered, that picture is decoded if it belongs to an initialized layer and discarded if it belongs to an uninitialized layer.
The layer-wise startup process would decode the grey pictures in FIG. 3. Note that IRAP pictures in enhancement layers may reference pictures in lower layers while IRAP pictures in the base layer are not allowed to reference any other picture.
There are three types of IRAP pictures in HEVC, the instantaneous decoding refresh (IDR), clean random access (CRA), and broken link access (BLA) types.
An IDR picture in the base layer is an intra picture that refreshes the decoder. This means that neither the IDR picture nor any base layer picture that follows the IDR picture in the bitstream can have any dependency to any picture that precedes the IDR picture in the bitstream. There is no codeword (POC lsb) signaled for base layer IDR pictures in HEVC, instead the POC is set equal to 0.
The base layer CRA picture is an intra picture that in contrast to the IDR picture does not refresh the decoder. This allows for base layer pictures later in the bitstream to depend on base layer pictures before the CRA picture in the bitstream. These pictures that precede the CRA picture in output order are called leading pictures and are not allowed to be displayed after the CRA picture, only before. All leading pictures in HEVC must be identifiable by using special picture types.
Besides using a base layer CRA picture for random access it is also possible to use the CRA picture for splicing video streams where a particular base layer IRAP picture in the middle of a bitstream and all subsequent pictures are replaced by a base layer CRA picture with its subsequent pictures from another bitstream, see FIG. 4. Since the base layer CRA picture may have leading pictures, which become undecodable when the CRA picture is used for splicing, the HEVC standard has defined the BLA picture type to use for CRA splicing. During splicing the CRA picture is simply re-typed as a BLA picture, see FIG. 4. The BLA picture type instructs the decoder to discard the leading pictures, and this makes splicing work. Another alternative would have been to remove the leading pictures during splicing but then system buffer parameters would need to be recalculated since data has been removed.
POC lsb is signaled for every picture in HEVC except the IDR picture type, for this IRAP picture type the POC is set to 0. The POC msb is set to 0 for BLA pictures but the POC lsb are present in the BLA slice header and the POC of the BLA picture is set equal to the POC lsb. The POC for CRA pictures is calculated as described above using POC lsb and POC msb.
A very important rule in HEVC is that the POC of every picture in the same access unit must be identical. This rule makes it easy to detect access unit boundaries; as soon as the POC of two pictures are different they belong to different access units and it makes it easier to detect picture losses. This rule is generally referred to as the POC alignment rule.
Another rule regarding BLA and IDR pictures is that they reset the decoder. Among other things this flushes the decoder and forces all picture that have not yet been output to be output. Note that CRA pictures do not flush the decoder. This rule is generally referred to as the IRAP output rule.
Another rule regarding POC values is that the current picture and all its short-term reference pictures must be within a certain POC range which is half of the maximum value of POC lsb. If POC lsb is coded using 8 bits, the maximum value is 28−1=255 and the allowed POC range is 255/2=127. This rule is generally referred to as the POC range rule.
The POC alignment rule and the rule that IDR pictures always have POC equal to zero poses a problem that is solved by the poc_reset_flag in JCTVC-N1008_v3, see section F.188.8.131.52 in [2]. The problem is illustrated in FIG. 5, where the POC value of each picture 12, 14, 16, 22, 24, 26 is shown inside each picture (the following figures in this document also show their POC values inside each picture). Only one of the pictures 12 is an IRAP picture, this is the IDR picture in FIG. 5, all other pictures 14, 16, 22, 24, 26 are non-IRAP pictures. Assume now that the encoder has encoded a lot of pictures so the last POC is 1032. Remember that only the POC lsb is signaled in the slice header and if we assume that 8 bits are used to signal POC lsb, the last POC was signaled by the value 1032%256=8, while the POC msb of 1032−8=1024 was derived. Now the encoder wants to put an IDR picture 12 in the base layer 10 without making any enhancement layer picture 22 in the same access unit 30 IRAP.
The IDR picture 12 sets the POC to 0, and the POC alignment rule says that all pictures 12, 22 in the same access unit 30 must have the same POC value. This means that both pictures 12, 22 in the access unit 30 containing the IDR picture 12 must have POC equal to 0. One problem here is that the enhancement layer picture 22 uses the picture 24 in the enhancement layer 20 with POC equal to 1032 for reference and this would violate the POC range rule given that picture 24 with POC 1032 is a short-term picture (1032−0>127). Another problem is that if the POC is set to 0 for the enhancement layer picture 22, that picture 22 gets a lower POC than the picture 24 with POC 1032, which would indicate that the enhancement layer picture 22 should be output before the picture 24 with POC 1032. This is not a problem for the base layer 10 due to the IRAP output rule but it is a problem for the enhancement layer picture 22.
The poc_reset_flag in JCTVC-N1008_v3 [2] solves this problem. The poc_reset_flag is a flag in the slice header of enhancement layer pictures that has the following effect on the decoder:                a) The POC is derived normally, deriving the POC msb and using the POC lsb as signaled in the slice header.        b) Then, the POC of every reference picture is decremented by the derived POC value.        c) Finally, the POC of the enhancement layer picture is set equal to 0.
Signaling a POC lsb of 10 (POC=POC msb+POC lsb=1024+10=1034) for the enhancement layer picture 22 of the access unit 30 containing the IDR picture 12 would result in the POC numbers shown in FIG. 6 after step a has taken place and FIG. 7 shows the POC numbers after steps a, b, and c have taken place. In practice not all pictures shown with negative POC values are still reference pictures at the time steps a, b, and c are carried out in this example, but here we assume that they are.
As you can see, FIG. 7 shows that the problem of POC range and output are both solved by the poc_reset_flag. For instance, the correct output order is maintained and first a picture 16, 26 with POC 20=−4 is output prior to a picture 14, 24 with POC=−2 and finally a picture 12, 22 with POC=0. The POC range is also correct since 0−(−2)=−2−(−4)=2<127. The poc_reset_flag is sent in the slice header extension part of HEVC. This is a part of the HEVC slice header that will be ignored by legacy or first version HEVC decoders.
There are, however, a number of problems with the existing solution in terms of error resilience problem, non-existing picture problem, temporal layer problem and bit cost problem.
The Error Resilience Problem
Consider the video stream shown in FIG. 8. If picture X 22 is lost during transmission, chances are that the POC of picture Y 21 is calculated based on the picture 24 with POC 1032. It would then get POC equal to 1026 (POC msb=1024 and POC lsb=2). Since the poc_reset_flag is carried in picture X 22, which is lost, no recalculation of POC values are done. The loss of picture X 22 therefore causes the following problems:                Picture Y 21 gets POC 1026, which violates the POC alignment rule (1026≠2).        Picture Y 21 gets POC 1026, which is lower than 1032, and the relative output order is incorrect.        If poc_reset_flag would have been received, POC 1032 would have been recalculated to −2. The POC of picture Y 21 would be 2 and therefore the reference picture set (RPS) of picture Y 21 would use a delta POC of −4 to indicate the reference picture. But POC of picture Y 21 is equal to 1026, which would specify a reference picture with POC 1022, which is incorrect.
The Non-Existing Picture Problem
Consider the video stream shown in FIG. 9. If the enhancement layer 20 has half the frame rate of the base layer 10, there is no corresponding picture to the IDR picture 12. This means that the POC cannot be reset in the enhancement layer 10 and the picture structure as shown in FIG. 9 is not possible.
The reason for not having an enhancement layer picture at the IDR picture is that a smaller maximum size of any access unit is desirable and the IDR access unit becomes smaller when there are no enhancement layer pictures there. A solution that would support this structure would be better than to forbid the shown picture structure.
The Temporal Layer Problem
Consider the video stream shown in FIG. 10. Here the enhancement layer consists of two temporal layers 20A, 20B to provide temporal scalability and picture X 42 is put in a higher temporal layer 20B. This is well if all pictures are received. However, if a node removes temporal layer 1 20A in the enhancement layer, the decoder faces the non-existing picture problem. Therefore, the picture structure in FIG. 10 is actually forbidden according to the prior art, which limits the encoder flexibility.
The Bit Cost Problem
Further, the current approach mandates that one bit in each slice header is used to signal poc_reset_flag. A more cost-effective solution is desired.
Thus, there is room for improvements with regard to scalable bitstreams, in which a video stream comprises pictures in multiple co-called layers.

Picture order count alignment in scalable video


A ceramic heater includes a silicon nitride ceramic substrate and a heating member embedded in the silicon nitride ceramic substrate. An Al-thickened layer is formed in a surface layer portion of the silicon nitride ceramic substrate. The Al-thickened layer has an Al concentration higher than that of an internal layer portion of the silicon nitride ceramic substrate. The Al-thickened layer assumes such a graded composition structure that the Al concentration increases toward the surface of the silicon nitride ceramic substrate.

1. Field of the Invention
The present invention relates to a ceramic heater for use in, for example, a glow plug, as well as to a method for manufacturing the ceramic heater.
2. Description of the Related Art
A conventional ceramic heater for use in, for example, a ceramic glow plug includes an insulating ceramic substrate and a resistance heating member embedded in the ceramic substrate and formed of, for example, a conductive ceramic material. Because of excellent thermal shock resistance and high temperature strength, silicon nitride ceramic is a popular material for the ceramic substrate.
As in the case of manufacture of many other ceramics, manufacture of silicon nitride ceramic employs a sintering aid. A sintering aid melts into a liquid phase during firing to thereby accelerate densification of a ceramic sintered body to be obtained, and plays a role in forming a grain boundary phase for bonding silicon nitride main phase (grains) of the ceramic sintered body. Sintering aids which are commonly used in manufacturing silicon nitride ceramic include magnesium oxide (MgO) and a combination of alumina (Al2O3) and yttria (Y2O3). However, these sintering aids involve a drawback in that a vitric grain boundary phase, whose softening point is low, tends to be formed in firing, and thus high temperature strength, particularly strength at 1200xc2x0 C. or higher, of an obtained sintered body tends to be impaired. When a rare-earth metal oxide and silica are added as sintering aids, the grain boundary phase can be crystallized to thereby contribute to enhancement of high temperature strength of a sintered body. However, since a liquid phase generated during firing exhibits poor fluidity, the sintering speed lowers. As a result, nonuniform sintering tends to occur, and thus variations in room temperature strength tend to occur among sintered bodies.
In order to cope with the above problems, Japanese Patent No. 2735721 discloses a silicon nitride ceramic heater whose manufacture employs a rare-earth metal oxide and alumina as sintering aids. Conceivably, addition of Al2O3 appropriately improves the sintering speed and increases the strength of the grain boundary phase.
However, in the technique disclosed in the above publication, since Al2O3 is added uniformly to the entirety of the ceramic sintered body, the softening point of the grain boundary phase tends to lower. Thus, high temperature strength unavoidably lowers. Also, since an Al component is contained in the form of Al2O3, the grain boundary phase tends to be vitrified, causing an adverse effect on the intended improvement of high temperature strength.
The present invention provides a ceramic heater comprising a silicon nitride ceramic substrate (hereinafter referred to as either a ceramic substrate or a substrate) and a resistance heating member embedded in the silicon nitride ceramic substrate. An Al-thickened layer is formed in a surface layer portion of the silicon nitride ceramic substrate. The Al-thickened layer has an Al concentration higher than that of an internal layer portion of the silicon nitride ceramic substrate.
According to the above configuration, the Al-thickened layer is formed merely in a surface layer portion of the ceramic substrate. Thus, even when the Al component causes lowering of the softening point of the grain boundary phase, the influence is limited to the surface layer portion of the ceramic substrate. Therefore, the high temperature strength of the ceramic substrate is unlikely to be impaired. Formation of the Al-thickened layer suppresses growth of silicon nitride main phase (hereinafter, referred to as may be called merely main phase) grains in the surface layer portion of the ceramic substrate, so that abnormally grown grains which provide a starting point of fracture are hardly produced. Therefore, the Al-thickened layer prevents variations in strength, particularly room temperature strength, among ceramic substrates.
Preferably, the thickness of the Al-thickened layer is 50 xcexcm to 1000 xcexcm. When the thickness is less than 50 xcexcm, variations in room temperature strength among silicon nitride ceramic substrates may fail to be effectively suppressed. When the thickness is in excess of 1000 xcexcm, sufficient high temperature strength may fail to be imparted to the ceramic substrate. More preferably, the thickness is 50 xcexcm to 500 xcexcm. Preferably, the Al-thickened layer assumes an average Al concentration of 0.1% to 5% by weight. When the Al concentration is less than 1% by weight, growth of main phase grains in the surface layer portion of the ceramic substrate may fail to be effectively suppressed, potentially causing variations in room temperature strength among ceramic substrates. When the Al concentration is in excess of 5% by weight, the high temperature strength of the Al-thickened layer itself may be impaired, potentially failing to attain enhancement of strength of the ceramic substrate intended by means of the Al-thickened layer.
When growth of main phase grains in the Al-thickened layer is effectively suppressed, the average grain size of the silicon nitride main phase in the Al-thickened layer becomes smaller than that of the silicon nitride main phase in an internal layer portion of the ceramic substrate. Preferably, the average grain size of the silicon nitride main phase in the Al-thickened layer is 0.1 xcexcm to 1 xcexcm, and that of the silicon nitride main phase in the internal layer portion is 0.2 xcexcm to 5 xcexcm. In either case, when the average grain size is below the lower limit, preparation of material powder for attainment of the average grain size becomes very difficult. When the average grain size is in excess of the upper limit, the strength of the ceramic substrate may become insufficient In order to suppress formation of a starting point of fracture, the maximum grain size of the main phase in the Al-thickened layer is preferably not greater than 10 xcexcm. Herein, the grain size is defined as follows. Various pairs of parallel lines are drawn tangent to the contour of a crystal grain observed on a sectional microstructure of the ceramic substrate, in such a manner as not to traverse the crystal grain. The distance between the parallel lines of each pair is measured. The maximum distance is defined as the grain size of the crystal grain.
The silicon nitride ceramic substrate assumes, for example, a microstructure such that Si3N4 grains are bonded by means of a grain boundary phase (bonding phase) derived from a sintering aid component, which will be described later. Preferably, the main phase is predominantly composed of an Si3N4 phase which contains xcex2-Si3N4 in an amount of not less than 70% by volume (preferably, not less than 90% by volume). In this case, the Si3N4 phase may be such that a portion of Si or N atoms may be replaced with Al or oxygen atoms and such that metallic atoms of, for example, Li, Ca, Mg, or Y, are incorporated into the phase in the form of solid solution. Examples of such a phase construction are sialon expressed by the following formulas.
xcex2-sialon: Si6-Si6AlzOzN8-z(z=0 to 4.2) xcex1-sialon: Mx(Si,Al)12(O,N)16(x=0 to 2)
where M represents Li, Mg, Ca, Y, or R (a rare-earth element other than La and Ce). Herein, unless otherwise specified, the term xe2x80x9cpredominantxe2x80x9d or xe2x80x9cpredominantlyxe2x80x9d used in relation to content means that the content of a substance in question is contained in an amount of not less than 50% by weight.
Preferably, a predominate portion of the Al component in the ceramic substrate is present in the form of an inorganic compound other than Al2O3. Specifically, it is preferable that the Al component be integrated into the main phase through replacing a silicon component as mentioned above and that the Al component present in the grain boundary phase assume the form of nitride or oxynitride or the form of composite nitride, composite oxide, or composite oxynitride with another sintering aid component. The Al component present in such a form suppresses vitrification of the grain boundary phase or further enhances suppression of growth of crystal grains in the main phase, thereby effectively suppressing impairment in the high temperature strength of the ceramic substrate. This effect is developed irrespective of whether or not the surface layer portion of the ceramic substrate is thickened with the Al component.
The present invention further provides a ceramic heater comprising a silicon nitride ceramic substrate containing an Al component and a resistance heating member embedded in the silicon nitride ceramic substrate. The Al component is present in the silicon nitride ceramic substrate predominantly in the form of an inorganic compound other than Al2O3.
Next, a sintering aid component is predominantly engaged in formation of the bonding phase; however, a portion of the sintering aid component may be integrated into the main phase. The bonding phase may contain unavoidable impurities; for example, silicon oxide contained in silicon nitride material powder, in addition to an intentionally added component serving as a sintering aid.
A sintering aid component usable in the present invention is not limited to a rare-earth component. For example, elements of Groups 4A, 5A, 3B, and 4B of the Periodic Table, such as Si and Al, can be used to such an extent as not to impair the effect of the present invention. The silicon nitride ceramic substrate to be obtained may contain a sintering aid component in an amount of 3% to 15% by weight on an element basis. When the content of the sintering aid component is less than 3% by weight, a dense sintered body is hardly obtained. When the content of the sintering aid component is in excess of 15% by weight, strength, toughness, or heat resistance may become insufficient. The content of the sintering aid component is preferably 6% to 10% by weight.
Rare-earth components usable in the present invention are Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. In particular, Tb, Dy, Ho, Er, Tm, and Yb can be favorably used, since the elements, when added, accelerate crystallization of the grain boundary phase and improve high temperature strength. Combined addition of a rare-earth component and the Al component synergistically suppresses abnormal growth of crystal grains in the main phase and variations in room temperature strength among ceramic substrates (in particular, the synergistic suppression becomes more effective when one or more rare-earth elements among Tb, Dy, Ho, Er, Tm, and Yb are used). Conceivably, this is because presence of the above rare-earth element(s) facilitates presence of the Al component in the form of an inorganic compound other than Al2O3. The synergistic effect is maximally yielded when the Al content of the ceramic substrate is 0.1% to 5% by weight, and the rare-earth component content of the ceramic substrate is 3% to 15% by weight.
In order to accelerate crystallization of the grain boundary phase, it is preferable that a rare-earth component serving as a sintering aid component be present in the form of a composite oxide with Si; specifically, the rare-earth component be contained in the form of R2SiO5 and/or R2Si2O7, where R is the rare-earth element. Whether or not the composite oxides are contained in a crystalline form can be confirmed by various known processes of crystal analysis; for example, X-ray diffractometry for measuring diffraction patterns, or selected area diffractometry using a transmission electron microscope.
In order to accelerate crystallization of the grain boundary phase, an excess silicon oxide component which is not involved in formation of the main phase must be contained in a necessary and sufficient amount. The excess silicon oxide component accelerates, for example, formation of crystals of the aforementioned composite oxide. The content of the excess silicon oxide component can be estimated from the amount of excess oxygen, which will be described below. The amount of sintering aid components, excluding Si and Al, contained in the ceramic substrate and the total oxygen content of the ceramic substrate are obtained. The amount of oxygen required for all the sintering aid components to be present in the form of oxide is subtracted from the total oxygen content. The thus-obtained amount of oxygen is defined as the amount of excess oxygen. In order to reliably yield the aforementioned effect through addition of a rare-earth component as a sintering aid component, the amount of excess oxygen is preferably 1% to 10% by weight on an SiO2 basis. When the amount of excess oxygen is less than 1% by weight on the SiO2 basis, sinterability is impaired. When the amount of excess oxygen is in excess of 10% by weight, the softening point of the grain boundary phase drops, potentially resulting in impairment in high temperature strength.
Preferably, the Al-thickened layer assumes such a graded composition structure that the Al concentration increases toward the surface of the ceramic substrate. Through employment of the structure, a compositionally discontinuous boundary portion is unlikely to be formed between the Al-thickened layer and the internal layer portion of the ceramic substrate, thereby further enhancing the strength of the ceramic substrate.
When a gradient is present in the Al concentration of the Al-thickened layer, the thickness t of the Al-thickened layer is defined as shown in FIG. 11. Specifically, an Al concentration curve is obtained through measurement in the direction of depth x from the surface of the silicon nitride ceramic substrate. The Al concentration curve is expressed by
C=F(x) . . . xe2x80x83xe2x80x83(1)
On the curve (1), CO is an Al concentration by weight measured on the surface of the substrate, and CB is an average Al concentration by weight of an internal portion of the substrate (CB may be substantially zero in some cases). A straight line is defined as follows.
C=CB+0.5 (COxe2x88x92CB) . . .xe2x80x83xe2x80x83(2)
On the x-C plane, the intersection B of the curve (1) and the straight line (2) is obtained (when a plurality of intersections are formed due to influence of noise appearing on the curve (1), the one closest to the substrate surface is selected). The x coordinate of the intersection B is defined as the thickness t of the Al-thickened layer. The Al concentration curve can be obtained by a so-called line analysis. In this line analysis, an analysis line AL is first defined on the cross section of the substrate in the above-mentioned x direction, and the concentration of Al is determined along the analysis line AL by making use of an electron probe X-ray microanalyzer (EPMA). The Al concentration curve is obtained as a profile of variation in characteristic X-ray intensity of the Al component along the analysis line AL. Herein, the characteristic X-ray intensity of the Al component is considered proportional to the Al concentration.
When a gradient is present in the Al concentration in the Al-thickened layer, the ratio CB/CO (hereinafter, may be called gradient) is preferably not greater than 0.9.
The above-mentioned ceramic heater having the Al-thickened layer can be manufactured by the following method of the present invention. The method comprises the step of firing a green body or a calcined body of the silicon nitride ceramic substrate while an Al component source substance is in contact with the surface of the green body or calcined body, to thereby form in a surface layer portion of the obtained silicon nitride ceramic substrate an Al-thickened layer having an Al concentration higher than that of an internal layer portion of the silicon nitride ceramic substrate. The method has the following advantages. The Al component is diffused from the surface of the substrate to thereby easily form the Al-thickened layer. Firing and formation of the Al-thickened layer can be carried out in a single process, thereby enhancing work efficiency. The Al concentration of the Al-thickened layer can be easily adjusted. Through unidirectional diffusion of the Al component, a gradient can be easily introduced in the Al concentration of the Al-thickened layer.
The above-mentioned firing process may comprise the steps of: forming a coating layer containing the Al component source substance on the surface of a cavity of a pressing die; and hot pressing the green body or the calcined body by use of the pressing die. A parting component may be contained in the coating layer containing the Al component source substance. In this case, in a process for applying a parting material to the surface of the pressing die, the Al component source substance can be simultaneously applied to the die surface, thereby shortening the manufacturing process.
In order to contain the Al component in the ceramic substrate in the form of an inorganic compound other than Al2O3 as mentioned previously, firing can be performed at a temperature not lower than 1700xc2x0 C. in a nitrogen atmosphere having a partial pressure of oxygen (contained, for example, as an impurity) of 0.01 Pa to 100 Pa and a partial pressure of nitrogen not lower than approximately 5xc3x97104 Pa (approx. 0.5 atmosphere).
Thus, it is an object of the present invention is to provide a ceramic heater whose silicon nitride ceramic substrate substantially maintains high temperature strength without impairment resulting from addition of an Al component, and featuring low variations in room temperature strength among silicon nitride ceramic substrates.
Another object of the present invention is to provide a method for manufacturing the above-described ceramic heater.
Various other objects, features and many of the attendant advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description of the preferred embodiments when considered in connection with the accompanying drawings

Ceramic heater and method for manufacturing the same


A method, implemented by a router device, for guiding a user in establishing access privileges for a data exchanger includes causing the data exchanger to establish a remote link with a data service provider. Access content is obtained from the data service provider and presented to a client device. Access data provided in response to the presenting of the access content is received. The access content when presented by the client device enables a user to supply the access data. The access data is useable by the data service provider to set access privileges associated with the data exchanger that enable the data exchanger to be utilized to perform a desired function. The access data is returned to the data service provider via the remote link. The data exchanger is utilized to implement the desired function.

Routers allow client devices in a local area network (LAN) to access a wide area network (WAN). Often, a router connects to the WAN via a data exchanger such as a data enabled cellular device, a DSL modem, or a cable modem. A given router may be equipped to simultaneously connect to multiple data exchangers. A data exchanger in the form of a data enabled cellular device is typically associated with a data plan allowing that device to be used to access the WAN. The data plan specifies cost, payment methods, access privileges, and the like. Access privileges can relate to data transfer rate and volume limitations, time of use limitations, as well as content limitations. For example, access privileges may limit transfer speeds to a fraction of the potential available to the data exchanger. Other access privileges may limit data transfers to a certain number of megabytes per time period. Yet other access privileges may limit the content or type of data that can be transferred. For example, access privileges may block or restrict communications from file sharing applications or the transfer of large files in general.
When presented with a new data exchanger, the data plan is typically inactive preventing the device from being used to access the WAN. Unfortunately, a user is not provided with the ability to efficiently activate or even modify a data plan.


A piezoelectric quartz plate having reduced frequency deviation as a function of temperature, wherein the quartz plate is cut at an angle described by:       T    f    =      3.9    +          6.5                    cos        2                  θ        +                  1        2                          [                                                            c                66                                                          T                                  c                  66                                                                          sin                2                                          θ                        +                                          c                44                                                          T                                  c                  44                                                                          cos                2                                          θ                        +                                          T                                  c                  14                                                                          c                14                                          sin                                            xe2x80x83                                          2                            θ                                                                          c                66                                                          sin                2                                          θ                        +                                          c                44                                                          cos                2                                          θ                        +                                          c                14                                          sin                                            xe2x80x83                                          2                            θ                                      ]              +          "AutoLeftMatch"                        [                                    a              xe2x80x2                        ·                          (                                                sin                                                        (                                                                  ω                        ·                        θ                                            +                                              φ                        xe2x80x2                                                              )                                                  +                                                      (                                          sin                                                                    (                                                                              ω                            ·                            θ                                                    +                                                      φ                            xe2x80x2                                                                          )                                                              )                                    2                                            )                                ]                +        δ

The present invention relates to the field of quartz plate oscillators, and, more specifically, to a method for determining angles of cuts that produce quartz plates having low shifts in frequency as a function of temperature, and the manipulation of that method to reduce the effects of other electrical components.
In 1980 the Curie brothers observed that when a permanently polarized material is subjected to a mechanical force an electric field is produced. Today, this phenomenon is referred to as the piezoelectric effect. Conversely, when an alternating electric current is applied to opposite faces of a piezoelectric crystal, the crystal expands and contracts in concert with the alternating electric current. Piezoelectric crystals typically resonate within narrowly defined frequency ranges and when suitably mounted they can be used in electric circuits as components of highly selective filters or as frequency-control devices for very stable oscillators.
As demand for space on the available radio-frequency spectrum grows, spacing between assigned frequencies has become tighter. To avoid interference between transmitters operating in the same geographical area or on adjacent channels, it is essential that frequency be accurately controlled.
The internal constraints of communication devices also demand small frequency deviation as a function of temperature, and as consumer demand continually drives down the size and the cost of this equipment, the need for smaller piezoelectric devices that can maintain tight temperature performance and that are less costly to manufacture becomes increasingly greater.
Due to its high Q value (a measure of the properties that give the quartz crystal its unique ability to control a frequency) and its low cost, quartz (SiO2) is the material of choice for the production of piezoelectric devices. Quartz plates are commonly used for frequency control in electronic devices such as computers, cellular phones, pagers, radios, and wireless data devices, and have been exploited to produce very accurate clocks.
Originally, quartz plates were made from natural quartz crystals, but today quartz plates are cut almost exclusively from synthetically produced quartz crystals. The orientation, or angle, of the cut with respect to the crystallographic axes X, Y, and Z (FIG. 1) determines how the oscillation frequency of the plate will be affected by temperature variations where temperature dependence is often expressed in terms of the temperature coefficient of frequency and by other properties of the resonator. In addition, the angle of cut determines the tolerance level, or margin of error, for a given cut. In mass production a low margin of error results in substantial increases in manufacturing costs and in the additional cost of providing corrections for errors made.
The X, Y, and Z crystallographic axis are often referred to as the electrical, mechanical, and optic axes, respectively. The earliest quartz crystal cut was made with the crystal""s major face perpendicular to the X-axis and with its length along the Y-axis. Whenever a cut is made so that the major face of the crystal plate is perpendicular to a particular axis, that cut is given the name of the axis to which it is perpendicular (FIG. 2). For example, when a cut in made so that the crystal""s major face is perpendicular to the X-axis, it is referred to as an X cut.
To eliminate the coupling effect that is inherent in X cuts, the angle of the X cut can be rotated 18.5xc2x0 from the Y-axis toward the Z axis (FIG. 3). The rotated X cut gives a good resonance free from other modes. It suffers, though, from the fact that, to get a reasonably high frequency from this type of length vibrating cut, too small a length to be practical is required.
Eventually a Y cut (a cut where the large crystal face is perpendicular to the Y axis) was developed. This cut, however, suffers from large changes in frequency with changes in temperature, i.e., the frequency increases about 86 ppm (parts per million) for each degree Centigrade increase in temperature. To reduce the temperature effect, the angles at which the Y cuts are made can be varied. When cuts are made at angles of either +35xc2x0 15xe2x80x2 or xe2x88x9249xc2x0 (rotated about the X axis) the first order, or linear portion, of the temperature coefficient of frequency is zero. A quartz plate cut at a +35xc2x0 15xe2x80x2 angle is referred to as an AT cut plate and a plate cut at a xe2x88x9249xc2x0 angle is referred to as a BT cut plate (FIG. 4).
The conventional mathematical description of quartz""s piezoelectric behavior as a function of temperature dates back to the early WWII efforts and is based on several simplifying mathematical assumptions. These simplifying assumptions (i.e., ignoring many of the properties that control the piezoelectric behavior of quartz) enable easy, though not definitive, calculation of the temperature coefficients of various cuts of quartz plates. For example, the original mathematical description published by Heising in 1946 (Quartz Crystals for Electrical Circuits, Raymond A. Heising, D. Van Nostrand Co. Inc. 1946, pg. 27), and republished in a restated form later by Salt (Hy-Q Handbook of Quartz, David A. Salt, 1983), is based on the assumption that all piezoids of quartz are equivalent and that their stiffness coefficients repeat 0xc2x0 to 90xc2x0, 90xc2x0 to 180xc2x0, 180xc2x0 to 270xc2x0, and 270xc2x0 to 360xc2x0. It is also based on the assumption that the mechanical vibrations in the crystal are ideal and perfectly elastic.
These assumptions led to the published (Quartz Crystals for Electrical Circuits, Raymond A. Heising, D. Van Nostrand Co. Inc. 1946 pg. 54) and commonly accepted equation:                               T          f                =                  3.9          +                      6.5                                      cos              2                                    θ                    +                                    1              2                                                  [                                                                                c                      66                                                                                T                                              c                        66                                                                                sin                      2                                                            θ                                    +                                                            c                      44                                                                                T                                              c                        44                                                                                cos                      2                                                            θ                                    +                                                            T                                              c                        14                                                                                c                      14                                                            sin                                                              xe2x80x83                                                            2                                        θ                                                                                c                      66                                                                                sin                      2                                                            θ                                    +                                                            c                      44                                                                                cos                      2                                                            θ                                    +                                                            c                      14                                                            sin                                                              xe2x80x83                                                            2                                        θ                                                              ]                                                          (        1        )
where:
Tf=frequency temperature coefficient,
xcex8=angle of rotation from the Z axis,
cxx=is the value of stiffness. The subscripts denote the stiffness of a given rhombohedral axis.
This equation uses the older IRE (Institute of Radio Engineers) convention of designating the xe2x80x9cATxe2x80x9d cut as a positively rotated Y cut. Subsequent publications by Bottom (Introduction to Quartz Crystal Design, Virgil Bottom, Van Nostrand Reinhold Co. 1982) and by Salt (Hy-Q Handbook of Quartz, David A. Salt, 1983) updated the formulation to use the more modern sign convention that produces the familiar curve giving the relationship of temperature coefficient to angle of cut (FIG. 5). This graph shows zero frequency temperature coefficient points for the first order approximation at the familiar AT and BT cut angles. The commercial success of the AT cut in comparison to the BT cut lies in the fact that for the AT cut not only is the first order temperature coefficient zero but its second order temperature coefficient is also zero. This condition gives the AT cut a much lower total frequency deviation as a function of temperature compared to the BT cut.
The AT cut provides a low cost quartz plate with good frequency-temperature performance. The AT cut, although widely used, does not perform well when mechanically and thermally stressed. This shortcoming can be reduced by using a doubly rotated cut. A doubly rotated cut is obtained by starting with a traditionally rotated Y cut, with its initial rotation about the X axis through an angle xcex8, followed by a second rotation about the new Z axis (referred to as Zxe2x80x2 and is defined by the crystallographic axes of the rotated plate) through an angle xcfx86. Thus, a doubly rotated cut is defined by the angles xcfx86 and xcex8, where in the case of an AT cut the xcfx86 is zero.
A third rotation, referred to as an in-plane omega rotation, is sometimes used to separate unwanted vibrational modes from the main mode. An omega rotation is made in the plane of either a singly or a doubly rotated cut. For example, after a plate is oriented by a rotation oft theta equal to 44 degrees and another with phi equal to 12 degrees, the plate is then rotated within the plane so that the length of the plate is not exactly along either the x or z axis, but resides somewhere between the x and z axes.
These improvements none withstanding, the modem trend is for tighter and tighter frequency-temperature performance from piezoelectric resonators. This requirement has resulted in the use of external temperature compensation schemes being applied to systems utilizing AT-cut quartz resonators, which increases cost, time, and system complexity. There are other angles of cut, but they all suffer from either strong frequency dependence on temperature or on the presence of competing modes of vibrations.
It is clear then that there exits a need for additional angles of cut that will reduce the frequency dependence on temperature and on the presence of other modes of vibrations. It is also clear that there is a need for a way to determine, without undue experimentation, which angles of cut will produce desired results.
The present invention generally provides for piezoelectric quartz plates having reduced frequency deviation as a function of temperature, wherein the quartz plates are cut at an angle described by:                               T          f                =                  3.9          +                      6.5                                      cos              2                                    θ                    +                                    1              2                                                  [                                                                                c                      66                                                                                T                                              c                        66                                                                                sin                      2                                                            θ                                    +                                                            c                      44                                                                                T                                              c                        44                                                                                cos                      2                                                            θ                                    +                                                            T                                              c                        14                                                                                c                      14                                                            sin                                                              xe2x80x83                                                            2                                        θ                                                                                c                      66                                                                                sin                      2                                                            θ                                    +                                                            c                      44                                                                                cos                      2                                                            θ                                    +                                                            c                      14                                                            sin                                                              xe2x80x83                                                            2                                        θ                                                              ]                                +                      "AutoLeftMatch"                                          [                                                      a                    xe2x80x2                                    ·                                      (                                                                  sin                                                                          (                                                                                ω                              ·                              θ                                                        +                                                          φ                              xe2x80x2                                                                                )                                                                    +                                                                        sin                                                                                (                                                                                ω                                ·                                θ                                                            +                                                              φ                                xe2x80x2                                                                                )                                                                          2                                                              )                                                  ]                            +              δ                                                          [        2        ]
where
Tf=frequency temperature coefficient,
xcex8=angle of rotation from the Z axis,
cxx=is the value of stiffness. The subscripts denote the stiffness of a given rhombohedral axis,
xcfx89=the angular velocity of the wave traversing the crystal face,
axe2x80x2=the amplitude of the wave traversing the crystal face,
xcfx86xe2x80x2=the phase delay imposed on the wave traversing the crystal face due to resistance by its surroundings, and
xcex4=offset value between the idealized wave and the wave with a damping function.
Accordingly, a primary object of the present invention is to provide quartz plates having reduced vibrational frequency dependence on temperature and on other modes of vibrations that are present, where the quartz plates are for use in electric circuits as components of highly selective filters or as frequency-control devices for very stable oscillators, such as is required by computers, cellular phones, pagers, radios, and wireless data devices, and very accurate clocks.
A secondary object of the present invention is to provide for a method to determine angles of cut for the cutting of quartz plates wherein quartz plates having reduced frequency dependence on temperature and on other modes of vibrations present are produced.
A further object of the present invention is to provide for a method to determine angles of cut for the cutting of quartz plates wherein quartz plates having a desired margin of error are produced.
Another object of the present invention is to provide for a method to determine angles of cut for the cutting of quartz plates from quartz crystals wherein quartz plates having properties that will correct effects from other electronic components present.
These and other objects, features, and advantages of the present invention will become apparent upon a reading of the detailed description and claims in view of the several drawing figures.

Piezoelectric quartz plate and method of cutting same

Abstract: where quartz plate thickness is chosen in accordance with a desired frequency. This useful behavior can be manipulated such that a quartz plate is designed to counteract frequency shifts over temperature excursion of other electrical components found in typical oscillator circuits. The choice of angles of cut having larger margins of error means that quartz oscillators can be more easily reproduced on a large scale and at a lower cost than has traditionally been the case.


A plating method is capable of preferentially precipitating a plated film fully and uniformly in trenches and via holes according to a mechanical and electrochemical process, and of easily forming a plated film having higher flatness surface without being affected by variations in the shape of trenches and via holes. The plating method includes a first plating process and a second plating process. The second plating process is performed by filling a plating solution between an anode and a substrate, with a porous member placed in the plating solution, repeatedly bringing the porous member and the substrate into and out of contact with each other, passing a current between the anode and the substrate while the porous member is being held in contact with the substrate.

1. Field of the Invention
The present invention relates to a plating apparatus and a plating method, and more particularly to a plating apparatus and a plating method used for filling a fine interconnect pattern formed in a substrate, such as a semiconductor wafer, with metal (interconnect material), such as copper, so as to form interconnects.
2. Description of the Related Art
Recently, there has been employed a circuit forming method comprising forming fine recesses for interconnects, such as trenches or via holes in a circuit form, in a semiconductor substrate, embedding the fine recesses with copper (interconnect material) by copper plating, and removing a copper film (plated film) at portions other than the fine recesses by CMP means or the like. In this method, from the viewpoint of reducing loads on subsequent CMP, it is desirable that a copper plated film be deposited selectively in trenches or via holes in a circuit form, and that the amount of copper plated film deposited on portions other than the trenches or via holes be small. In order to achieve such an object, there have heretofore been proposed various ideas regarding a plating solution, such as composition in a bath of a plating solution or a brightener used in a plating solution.
A plating apparatus having the following configuration has been known as this type of plating apparatus used for plating to form fine interconnects having high aspect ratios. A substrate is held in such a state that a surface (surface to be plated) of the substrate faces upward (in a face-up manner). A cathode is brought into contact with a peripheral portion of the substrate so that the surface of the substrate serves as a cathode. An anode is disposed above the substrate. While a region between the substrate and the anode is filled with a plating solution, a plating voltage is applied between the substrate (cathode) and the anode to plate a surface (surface to be plated) of a substrate (for example, see Japanese laid-open patent publication No. 2002-506489).
In a plating apparatus in which a substrate is held and plated in single wafer processing while a surface of the substrate faces upward, a distribution of a plating current can be made more uniform over an entire surface of the substrate to improve uniformity of a plated film over the surface of the substrate. Generally, the substrate is transferred and subjected to various processes in such a state that a surface of the substrate faces upward. Accordingly, it is not necessary to turn the substrate at the time of plating.
Meanwhile, in order to deposit a copper plated film selectively in trenches in a circuit form or the like, there has been known a method of bringing a porous member into contact with a substrate such as a semiconductor wafer, and plating the substrate while relatively moving the porous member in a contact direction (for example, see Japanese laid-open patent publication No. 2000-232078).
In the prior art, however, when plating is performed, the amount of plated material is different in regions of the surface of the substrate depending on the shape of the interconnect pattern, such as trenches and via holes, under the influence of distribution of current density or the influence of additives, and hence it is difficult to form a plated film having a uniform thickness over the entire surface of the substrate. For example, a plated film deposited on an interconnect section having a dense fine interconnect pattern (trenches) is thicker than a plated film deposited on other portions, and a phenomenon called an overplating phenomenon generally occurs. On the other hand, the amount of plated material deposited on an interconnect section having a wide interconnect pattern (trenches) is generally smaller than that on other portions. As a result, in a case where an interconnect pattern is filled entirely with interconnect material such as copper by plating, the thickness of a plated film differs depending on the locations, causing irregularities of the surface of the plated film. When plating is performed according to such method, a greater amount of plated material than necessary is deposited, and hence raw material cost increases and a longer period of plating time is required. Further, loads on a polishing process, such as CMP or the like, after plating increase, and in the next generation in which a low-k material is used as an interlevel dielectric layer, a polishing apparatus will require a considerably high performance. Therefore, it is desirable that the plated film having higher surface flatness is deposited without being affected by variations in the shape of interconnect patterns.
It is desirable to fill up all interconnect patterns (trenches and via holes) uniformly with an interconnect material such as copper or the like, thereby forming interconnects that are free of voids therein. However, it is generally difficult to fill up trenches, particularly for interconnects that are fine and have a high aspect ratio, uniformly with an interconnect material such as copper or the like. It is more difficult to meet the above requirement for depositing a plated film having higher surface flatness without being affected by variations in the shape of interconnect patterns.
In order to solve the above problems, efforts have been made to improve plating solution details such as the composition of a plating bath, a brightener used in the plating solution, etc., and also to improve current conditions. Though these improvements are effective to a certain extent, they are not sufficient to solve the problems, and there are certain limits placed thereon at present.
If finer interconnects are to be formed, then it is preferable to individually perform plating which employs a plating solution suitable for filling finer interconnect patterns and plating which employs a plating solution suitable for reducing overplating. To meet such a need, two plating cells are generally required. Therefore, the plating apparatus not only needs a larger footprint, but also has an increased processing period as it is necessary to transfer substrates between the two cells.


A spin transistor having wide ON/OFF operation margin and producing less noise is provided. The spin transistor includes a substrate having a channel, a source, a drain and a gate formed on the substrate. The source and the drain are formed to have magnetization directions perpendicular to the length direction of the channel. The ON/OFF operations of the spin transistor can be controlled by generating a spin-orbit coupling induced magnetic field to have a direction parallel or anti-parallel to the magnetization directions of the source and the drain.

1. Field of the Invention
The present invention relates to a spin transistor using a spin-orbit coupling induced magnetic field, and more particularly, to a spin transistor having a wide ON/OFF operation margin and making less noise that is generated by leakage magnetic field.
2. Description of the Related Art
A metal oxide silicon field effect transistor (MOSFET) is one of representative elements in a modern integrated circuit technology. The MOSFET is generally included as an essential element for performing ON/OFF switching operation in a memory device such as a flash memory and a DRAM, as well as a logic circuit, ASIC and a microprocessor. Recently, a spin transistor (Spin-FET) is introduced. A conventional semiconductor based transistor controls only electric charge formed in the semiconductor using electric field. On the contrary, the spin transistor simultaneously controls electric charge and its spin. The spin transistor can be used in a switching element and a logic circuit by control of spin-polarized charge.
Though the MOSFET is currently used as an essential element in a semiconductor field, it has several drawbacks. For example, it is difficult to further reduce power consumption and volume of the MOSFET. In addition, the gate oxide of the MOSFET faces physical limitations. In order to overcome such limitations of the MOSFET, transistors that control spin-precession of electric charge with the voltage are introduced. Among them, a spin transistor includes a source, a drain and a channel connecting the source and the drain. A quantum well layer may be used as the channel in the spin transistor.
In a conventional spin transistor, magnetization directions of a source and a drain are identical to a channel direction, that is, a traveling direction of an electron (refer to Datta-Das spin FET in Applied physics letter, vol. 56, 665, 1990, and U.S. Pat. No. 5,654,566 issued to Mark B. Johnson entitled "MAGNETIC SPIN INJECTED FIELD EFFECT TRANSISTOR AND METHOD OF OPERATION"). In the conventional spin transistor, spin information of the electron is likely to be lost by stray field generated at the ends of the source and the drain. The generated stray field shortens an effective distance of spin transfer and makes considerable noise.
The conventional spin transistor controls a spin direction of an electron reached at the drain to be parallel or anti-parallel to the magnetization direction of the drain by controlling a "spin-precession" of an electron. By control of the spin-precession of the electron, the resistance of the channel is adjusted. However, it is very difficult to precisely adjust an angle of the precession and to accurately form the channel to have a proper length corresponding to the precession angle. Therefore, the conventional spin transistor has a narrow ON/OFF operation margin and allows a narrow process margin for the channel length. As a result, operating accuracy degrades and a manufacturing process thereof becomes complicated.

Spin transistor using spin-orbit coupling induced magnetic field

Korea Institute of Science and Technology


This disclosure relates to fluid delivery devices which include a body defining a fluid channel with filtration. In one embodiment, the body is molded to include a barrier which extends across the fluid channel and a series of apertures or openings are formed through the barrier. A laser device may be used to form the apertures through the barrier.

1. Technical Field
The present disclosure relates to fluid delivery devices for medical use. More particularly, the present disclosure relates to fluid delivery devices, such as needle assemblies or syringes, which include integral structure for providing fluid filtration.
2. Background of Related Art
Fluid delivery devices for communicating or directing a fluid to a desired location are well known in a variety of different technological areas. In the medical arts, fluid delivery devices include syringes, luer hubs, stopcocks, intravenous ("I.V.") line connectors, feeding set connectors and the like. Such devices are typically used to supply a parenteral solution from a source, such as a syringe, to a patient. As used herein, parenteral solutions is intended to refer to any solution intravenously or intramuscularly fed to a patient, such as via a syringe or intravenous infusion set.
Liquid formulations of drugs are seldom stable over prolonged periods of time. Thus, it is common for a drug to be provided in solid form, e.g., lyophilized (freeze dried), dehydrated or crystalline form. Such drugs require reconstitution, i.e. mixing the drug with a diluent, e.g., a dextrose solution, a saline solution or water, before the drug can be delivered to a patient. This can be accomplished by injecting the diluent into a vial containing the drug in solid form and thereafter shaking the vial or allowing the vial to sit for a predetermined period of time to ensure dissolution of the drug and the diluent. After the drug has been reconstituted, the drug can be withdrawn from the vial using, for example, a syringe, and delivered intravenously to a patient.
One problem associated with the above-described process is the presence of particulate contamination in the parenteral solution infused or injected into patients and the possible harm it may cause to a patient. Particulate contamination may also result from damaged syringes or the like unrelated to reconstitution of drugs. In order to minimize the risk associated with particulate contamination, it is known to press-fit a stainless steel mesh having, for example, 100 count mesh into an aluminum needle hub. Although such needle hubs provide filtration, the provision of a secondary filter in the needle hub, or like fluid devices, is costly.
Accordingly, a continuing need exists for a less costly fluid delivery device for delivering parenteral solutions which provides filtration.


The combination of an umbrella and cooler or carrier vessel comprising a main mast, a flexible umbrella frame operatively arranged at one end of the mast, means to maintain the flexible frame of the umbrella in spaced apart stand-off relation with respect to the main mast when the umbrella is collapsed and lowered, a vessel arranged at the opposite end of the mast and surrounding it, the distance of the side walls of the vessel from the mast and the distance at which the flexible frame of the umbrella is maintained from the mast by the spacing stand-off means being approximately equal to permit the flexible umbrella frame to surround the vessel.

Telescopically collapsible umbrellas have been in use before in this art. In the ordinary umbrella, such as is well known in the art, the usual light folding flexible frame of spring steel ribs is disposed in "spoke-like" arrangement to form a supporting frame which is usually covered with a rain and sun resisting fabric or other flexible material suitably fastened thereto. A slotted ferrule slides up and down the mast and carries ribs which are pivotally connected to the fabric supporting ribs, as well as to the ferrule. Spring latch means protrude, and are urged outwardly, from the mast at suitable places. One latch is located near the upper end of the mast, over which the ferrule passes, and engages the under side of the ferrule to maintain the umbrella in open or raised position. Another spring latch is located toward the lower end of the mast, adapted to protrude through the slot of the ferrule and maintain the umbrella in closed or collapsed position.


A method of wind tunnel measurement of airfoil, includes a step of providing a wind tunnel test apparatus. The wind tunnel test apparatus includes two walls, two supporting members, and two load measuring units. The method further includes steps of: coupling both ends of an airfoil model under test with the two supporting members, respectively; generating a flow of a fluid in the wind tunnel flow path; and measuring a load applied to the airfoil model by using the two load measuring units. A thin film member is stuck on each end of the airfoil model so that a part of the thin film member protrudes from the each end of the airfoil model along an outer circumference throughout an entire circumference. The thin film member has a strength at which the thin film member enables to endure a pressure of the fluid, and is formed of a material which is elastically deformable. The thin film member is provided so that a gap between the each end of the airfoil model and one of the two walls facing to the each end of the airfoil model is blocked.

1. Field of the Invention
The present invention relates to a method of wind tunnel measurement of airfoil, and more particularly relates to a method of wind tunnel measurement of airfoil, which is used for in a windmill, an aircraft, a turbine and the like.
2. Description of Related Art
As an apparatus that uses a blade, a windmill, an aircraft, a turbine and the like are known. The blade of the windmill, the aircraft or the like is high in aspect ratio (fineness ratio) (e.g., 10 to 20 or more). For this reason, in many cases, the aerodynamic design and the calculation of the aerodynamic performance of the entire blade are carried out by determining the aerodynamic performance of a two-dimensional airfoil section and integrating it in a blade width direction and then estimating a three-dimensional performance. In that case, it is necessary to carry out a wind tunnel test under a condition close to an actual use condition to get the aerodynamic characteristics of the two-dimensional airfoil section.
One of the conditions for the wind tunnel test is to secure the two-dimensional flow property. The flow of the fluid in the actual entire blade is three-dimensional. However, as mentioned above, the aspect ratio of the actual blade is high. Thus, from the viewpoint of each blade element, the flow of the fluid can be considered to be two-dimensional except the blade ends. Hence, in the wind tunnel test, it is important to remove the three-dimensional flow property of the fluid and secure its two-dimensional flow property.
As a related technique, Japanese Patent Publication No. JP-A-Heisei 9-210839 discloses a wind tunnel test apparatus for a structure. This wind tunnel test apparatus for a structure includes: a wind guiding path through which air flows; a model which is arranged in the wind guiding path and has an axis serving as a rotation center; a suspending wire suspending and holding the model in the wind guiding path; a detector which detects various forces generated in the model through the suspending wire when the model receives the flow of air; a model rotating mechanism which has a motor and a decelerator interlocking with the motor and rotates the model around the axis to change an orientation of the model with respect to a direction of the flow of air; and an actuator which is remotely operated. This wind tunnel test apparatus is characterized by containing a fixing mechanism for fixing the model in an orientation determined by the model rotating mechanism.
The inventors have now discovered the following facts.
The inventors have studied the following method as a method of a wind tunnel test. FIG. 1 is a schematic view showing the method of the wind tunnel test studied by the inventors. As shown in FIG. 1, a wind tunnel test apparatus 101 includes two walls 102, two supporting members 104 and two load cells 103. Each of the two walls 102 has a flat surface parallel to an x-direction. The two walls 102 are arranged at a predetermined distance from each other in a z-direction. The space between the walls 102 configures a wind tunnel flow path. An airfoil (airfoil model 111) under test is arranged in the wind tunnel flow path. A fluid (air)) for the wind tunnel test flows through the wind tunnel flow path. The upper supporting member 104 is arranged to penetrate through the upper wall 102 in the z-direction and not to interfere with the upper wall 102. The lower supporting member 104 is arranged to penetrate through the lower wall 102 in the z-direction and not to interfere with the lower wall 102. In the upper supporting member 104, one end is coupled with the top end of the airfoil model 111, and the other end is coupled with the upper load cell 103. In the lower supporter 104, one end is coupled with the bottom end of the airfoil model 111, and the other end is coupled with the lower load cell 103. The two load cells 103 fix the airfoil model 111 in the z-direction through the supporting members 104, respectively. The load cells 103 measure loads in the x-direction and the y-direction that are applied to the airfoil model 111 at the time of the wind tunnel test. The airfoil model 111 has the shape in which the airfoil is cut away in the two flat surfaces vertical to the longitudinal direction of the airfoil. The two supporting members 104 are connected to both ends of the airfoil model 111 that correspond to the two cutaway surfaces, respectively.
In this way, when the airfoil model 111 is placed inside the wind tunnel flow path and then the load is measured by using the load cells 103, a pair of balances or the like, it is considered that the following case occurs. That is, the airfoil model 111 is moved in the z-direction, then the airfoil model 111 is brought into contact with the surface of the wall 102, and consequently the load in the airfoil model 111 cannot be properly measured. Thus, in order to avoid the influence on the z-direction displacement of the airfoil model 111, it is required to form a gap between the airfoil model 111 and each of the two walls 102. FIG. 2 is a schematic view showing a relation between the airfoil model 111 and the wall 102. As shown in FIG. 2, a gap with an interval d1 is formed between the airfoil model 111 and the wall 102. For example, in the case of the airfoil model 111 having an airfoil chord length of 1500 mm, the interval d1 is approximately 10 mm.
However, with the existence of this gap, there is a possibility that a gap flow 110 occurs and/or an airfoil tip vortex (not shown) increases. Here, the gap flow 110 is the flow that the fluid moves from the side of a positive pressure surface to the side of a negative pressure surface in the airfoil model 111. In that case, the flow of the fluid is not two-dimensional originally scheduled but three-dimensional. This results in the loss of the lifting power of the airfoil model 111. Thus, it is difficult to obtain the aerodynamic characteristics of the two-dimensional airfoil section that is originally purposed.

Method of wind tunnel measurement of airfoil


A stand-alone portable alarm update tool includes a memory interface for receiving a computer readable memory; a serial port for interconnection to a security alarm panel, by way of a complementary port; a processor; and processor readable memory in communication with the processor, storing software adapting the processor to upload and download configuration files from a removable memory received by the memory port, to the alarm panel, by way of the serial port. Conveniently, the tool may be packaged in a hand-held casing, and which may also house a battery. In this way, the tool may be readily transported by an installer, without being unnecessary heavy or bulky.

Home and business alarms have become commonplace. Such alarms (often referred to as "security systems" or "alarm systems") typically include several sensors used to monitor unauthorized entry and other conditions at monitored premises, such as fire, smoke, toxic gases, high/low temperature (e.g. freezing) or flooding, at a premises. In response to sensing an alarm condition, one or more of these sensors provides a signal to an alarm panel that in turn may sound and notify the occurrence of the alarm to occupants of the premises and remotely signal a monitoring station or other third party. Modern alarm panels typically include a processor, under software control.
Typically the occurrence of an alarm is signalled to a remote monitoring station that may then dispatch capable authorities to intervene at the premises. For example, in the case of sensing an unauthorized entry to the premises, the monitoring station may dispatch security personnel, typically in the form of private security guards or police officers.
In order for the alarm system to properly signal the monitoring center, the system must be properly installed and configured. Installation requires installing the central panel; placing sensors; ensuring the sensors and panel are provided with a source of power; connecting the central panel with a communications network; pairing the sensors to the panel; and programming the panel to place a communication to the monitoring center in the case of an alarm.
In view of the complexity of properly installing and configuring a typical alarm system, errors are often made. To facilitate configuration of such system, modern panels—themselves small computing devices—may be interconnected to an external computing device, such as a laptop computer, to allow setting of configuration variables, and the loading of software. Commercially available software, such as for example the DSC® DLS-2002 download software (the "DLS software") is suitable for programming panels, storing configuration files, and uploading and downloading such files.
Likewise, configuration files in the form of updated software/firmware loads often need to be installed in order to keep the panel up to date, with the most recent software firmware loads that often include bug fixes, firmware updates, and the like. Again such software/firmware updates may be accomplished using an external computing device.
Unfortunately, transporting a computing device to an install premises is often cumbersome. Installers are often loath to transport the weight and bulk of a full-fledged computing device to an installation premises.
Accordingly there is a need for a portable, light weight configuration and installation tool.

Portable alarm configuration/update tool


A threshold protector to be used during the construction of a house or building is an apparatus made of durable material covering the threshold, contacting the back and front of the threshold and removably attached to the threshold.

During the construction of houses and buildings doorframes are installed in the building at an early stage. After installation, workers tread upon the threshold in shoes or boots, that carry mortar, dirt and rocks on the soles, Workers wheel or drag equipment into the house or building subjecting the threshold to scraping and impact. Bricks may be placed on the threshold or fall onto the threshold by workmen installing the exterior brick. Mortar, paint and chemicals, such as lacquer or thinner, can drip onto the threshold during varying phases of construction resulting in discoloration or damage. During the acid wash of the exterior brick, hydrochloric acid can fall onto the threshold causing additional discoloration or damage.
Removing dirt, rocks, mortar, paint, thinner, lacquer or acid discoloration from the threshold of a doorway takes one worker from fifteen to thirty minutes per doorway. In a typical residential construction with three doorways, three quarters of one man hour to one and one-half man hours of labor are required for the clean-up. Moreover, the clean-up work cannot remove scratches or dents. If a drop cloth is thrown over the threshold, it may not stay in place, or it will wear out before the construction is completed. More importantly, a drop cloth will be a hazard for workers who may trip over the loose material thereby causing increased expenses through on the job injuries and lost time. Putting tape on the threshold requires a good deal of time and will not survive the entire construction cycle due to the traffic and loads to be borne. Therefore, a need exists for an inexpensive disposable threshold protector that will have sufficient durability to last the entire construction period of the house or building.
Additionally, protection of thresholds is beneficial during moving of furniture, installation of new doors and during remodeling of existing buildings.
The prior art does not disclose such a protector. There are many examples of thresholds; however, no device has been patented to provide for the protection of the threshold during the construction of the house or building. U.S. Pat. No. 4,492,062 to Levenez discloses a window sill assembly for protecting and covering an existing window sill at the base of the window. The device is meant for permanent installation and is not adaptable to door thresholds.


A closed kneader mixing machine including a tilting mixing chamber and a pair of counter-rotating intermeshing rotors rotatably mounted within the tilting mixing chamber. Each rotor is a hollow cylinder having a spiral wing on the hollow cylinder with a pain of nogs proximate each end of the hollow cylinder. The counter-rotating intermeshing rotors may be synchronous rotors.

This invention relates generally to batch type polymer mixers and more particularly to a kneader mixer with intermeshing rotors.
There are two different types of internal mixers used in the industry at large. The first type is more commonly known as a "Banbury" type intensive mixer and the second type is known as a "Kneader". The primary difference between the two types of mixers is the rotor, throat, chamber and floating weight design. Banbury® mixers also discharge the batch through a bottom door where as the kneader tilts to discharge the batch.
A closed kneader is composed of a kneading tank or chamber for holding kneaded material, a pair of rotors, which are provided at both ends with rotor drive shafts passing through side walls of the chamber, and which consist of a rotor shaft forming a rotor blade for kneading the material kneaded in the chamber, and a pressure cover. When kneading material, the kneaded material is poured into the chamber when the pressure cover is opened upward. The pressure cover is let down and the rotors are rotatably driven with a driving means such as a motor, etc., connected, to the rotor drive shafts.
Traditional kneaders have two counter rotating rotors with each mixing rotor having two thin wings affixed on it. The two wing rotors typically rotate at different speeds through connecting gears. The wings move material from one portion of the chamber to the other while also providing material movement along the rotor axis. These kneaders do not have intermeshing rotors and therefore can have differential rotor speeds.
Typically, conventional kneaders have a one piece rotor design that includes a rotor shaft with two wings welded on the shaft. The conventional kneader's blades are typically long, high and narrow. Water cooling is provided through a passage in the rotor shaft and small jackets in each wing. This cooling method is usually not sufficient for single pass mixing.
During kneading, heat is produced within the kneaded material, in the chamber and also by the rotor shaft because of internal heat generation due to shearing, dispersion, etc., during kneading. For these reasons, insufficient cooling often occurs in the inner part of the kneaded material with respect to the kneading speed, i.e., the speed of heat generation, in the case of a kneaded material of large thickness and low thermal conductivity (especially rubber, etc.), even if cooling water is circulated through the chamber wall and the rotor shaft.
While sufficient cooling can be provided for the kneaded material with little increase of internal temperature in the kneaded material by using a kneader with a small mixing volume, such a machine is inferior in productivity and therefore unrealistic as a mass production unit.
In the closed kneader, while a general kneading process is divided into a primary kneading for mixing without containing any vulcanizing agent, and a secondary kneading for performing kneading by mixing the kneaded material, which has already been subjected to a certain kneading process in the primary kneading, with a vulcanizing agent, the kneading material temperature must be kept below a certain level (variable depending on the material) for mixing in the vulcanizing agent.
Generally, convention kneaders require processing a batch in two passes. Either by stopping the mixing and allowing the batch to cool before completing the mixing, or by discharging the batch into a second kneader.
Conventional kneaders typically use pneumatic pressure to push the batch down into the rotors and mixing chamber with a floating weight (ram). This pneumatic system can be unreliable and inconsistent. The pneumatic ram moves uncontrollably with the ram position being typically controlled by the rotor dragging force as well as the size of rubber or polymer pieces being forced into the rotors.
The foregoing illustrates limitations known to exist in present kneader mixers. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.

Intermeshing kneader with tilting mixing chamber


This disclosure relates generally to assessment of cognitive workload using breathing pattern of a person, where cognitive workload is the amount of mental effort required while doing a task. The method and system provides assessment of cognitive workload based on breathing pattern extracted from photoplethysmograph (PPG) signal, which is collected from the person using a wearable device. The PPG signal collected using the wearable device are processed in multiple stages that include breathing signal extraction to extract breathing pattern. The extracted breathing pattern is used for assessment of cognitive workload using a generated personalized training model, wherein the personalized training model is generated and dynamically updated for each person based on selection of a sub-set of breathing pattern features using feature selection and classification techniques that include maximal information coefficient (MIC) techniques. Finally based on personalized training model, the extracted breathing pattern is classified as high cognitive workload or low cognitive workload.

Cognitive or mental workload is the amount of mental effort required while doing a task. The cognitive workload directly affects the performance of an individual. A cognitive workload which is too high results in psychological conditions like stress, fatigue and anxiety, while low cognitive workload results in underutilization of one's mental resources. Hence based on cognitive workload the individual's performance declines if cognitive workload is too high or too low, resulting in mental fatigue or boredom. Therefore monitoring and assessing of an individual's cognitive workload is of immense importance to ensure effective and efficient performance standards.
The existing techniques for assessment of an individual's cognitive workload include questionnaire based assessments, numerous physiological correlates like brain activation, skin conductance and cardiovascular changes. The questionnaire based assessments may not be very effective as they are mostly structured instruments that allow little flexibility to the individual with respect to response format. Further the existing physiological correlates techniques can cause discomforts for the individual as sensors used are not unobtrusive and may not be easy to use. Further the physiological correlates techniques may not give very accurate results on complicated sensor data received. Further standardization of cognitive workload features may also not be very effective as each individual may have a different tolerance/threshold/features cognitive workload level.

Method and system for assessment of cognitive workload using breathing pattern of a person