An information processing apparatus for frequency domain optical coherence tomography comprises an image scanning unit that receives measurement data from an optical coherence tomography device, while moving a measurement point to the next adjacent point at each measurement time by controlling the optical coherence tomography device, and generates depth information based on the measurement data to produce a raw tomographic image. The apparatus includes a noise reduction unit that reduces noise from the raw tomographic image to produce a result tomographic image. The noise reduction unit reduces the noise from the raw tomographic image by subtracting the depth information generated by the image scanning unit at each measurement time from the depth information generated at another measurement time adjacent to said each measurement time.

Frequency domain or Fourier domain optical coherence tomography (FD-OCT) is an advanced tomography technology widely used in the medical diagnostic field. In particular, because the FD-OCT technology makes it possible to safely obtain tomographic images of retina and others, it is popular in the ophthalmology field, and is also used for coronary artery diagnosis or for endoscopy.
In addition to the medical field, the FD-OCT technology has also been used in various industrial fields, for example, measuring a thickness of a wafer and analyzing each layer of a picture to preserve the artwork. Optical-fiber-based optical coherence tomography is particularly useful not only for medial endoscopy but also for an industrial use, because it can be used in a hard-to-reach area such as radioactive contaminated environments.
The optical coherence tomography has a superior resolution compared to conventional medical imaging technologies such as MRI (Magnetic Resonance Imaging). Furthermore, FD-OCT has a good signal-to-noise ratio and is fast in measurement.
However, tomographic images generated using FD-OCT are susceptible to fixed horizontal stripe noise due to the DC spectrum of a light source. Thus, there have been researches for reducing such fixed pattern noise.
For example, a reference spectrum subtraction method reduces noise by obtaining the frequency spectrum of an optical power in a physical way and subtracting it from the depth information. However, this method is inconvenient due to the necessity for obtaining the DC spectrum of the light source before a sample scanning.
Some techniques that use software for subtracting fixed stripe noise has been introduced to solve the above inconveniences. Of those techniques, a mean-line subtraction method calculates the mean of the signals and subtracts the mean from each depth information signal. The median-line subtraction method is similar to the mean-line subtraction method except that it uses the median of the signals instead of the mean of the signals.
However, in the above-described conventional methods, if the intensity of the light source changes during measurement, i.e. while the depth information is obtained, noise cannot be reduced normally, which becomes a big problem particularly when an optical fiber is used for optical coherence tomography. By way of example, in the case of medial endoscopy, the intensity of the light source can fluctuate dynamically due to external circumstances such as heartbeats, blood circulation, and breathing. In particular, when an endoscopic tube is bent in a blood vessel, it can cause radical fluctuations in the light source.
Therefore, a need exists for providing an apparatus and a method for efficiently reducing noise, when an unstable light source is used or when the light source is fluctuating dynamically in an optical-fiber-based environment such as an endoscope.
In this regard, Korean Patent Laid-open Publication No. 10-2011-0036593 (entitled "Imaging apparatus and imaging method using optical coherence tomography, and computer readable storing medium") discloses an apparatus and method for reducing noise caused by a return light.
Also, Korean Patent Laid-open Publication No. 10-2006-0120165 (entitled "Method and apparatus for performing optical imaging using frequency-domain interferometry") discloses an apparatus and method for reducing shot noise.

Frequency domain optical coherence tomography image noise reduction by subtraction of adjacent depth data

KOREA UNIVERSITY RESEARCH AND BUSINESS FOUNDATION


Systems, devices, and methods are disclosed for securing a theft-susceptible movable object at a selected location. A security system is positioned at a selected location for protection of a theft-susceptible movable object. The security system includes a magnetic field source adapted to generate a magnetic field that is positionally-associated with a movable object. A monitoring device includes a magnetic sensor and is adapted for placement proximate to the selected location. The monitoring device is adapted to take one or more measurements of the magnetic field and to detect alteration in the measurements caused by movement of the magnetic field source relative to the monitoring device when the movable object is moved from the selected location. Upon detecting the alteration in the measurements of the magnetic field, the monitoring device is adapted to output an electronic warning signal indicating that the movable object has moved from the selected location.

Some valuable objects, such as jewels or precious metals, may be protected from theft or damage by locking them in vault or safe deposit box. However, for other valuable objects, it may be desirable for the objects to be kept in an open location so that they can be displayed or accessed. For example, it may be desirable to display artworks, such as paintings, sculpture, or fine pottery, antiques, cultural artifacts, or historical artifacts so that they may be readily enjoyed. Also, high quality electronics, such as laptop computers or high-quality audio or video components, should be readily accessible so that they can be used and enjoyed. Locking up artworks and various other valuable objects in safes, vaults, safe deposit boxes, rooms with restricted access, or other secured spaces would diminish the ability to enjoy them.
There are various ways to protect valuable objects without locking them in a vault or safe deposit box. For example, some artworks are locked in protective transparent cases. Additionally, museums may employ motion-based sensors that use lasers, infrared beams, or pressure sensors to detect movement occurring within an unacceptable proximity of the artwork. These sensors trigger an alarm when one or more persons come within a distance that is overly close to an artwork or impermissibly tries to touch or handle the artwork. Wall-mounted objects, such as paintings, may be hung on a device secured to the wall that is sensitive to movement of the painting and that will sound an alarm if the painting were to be lifted from its mounting. Sculptures or other objects that generally rest atop a surface may be protected by one or more pressure-sensitive pads placed beneath the object on a floor, pedestal, or other supporting surface, where the pressure-sensitive pads trigger an alert if the object is lifted from its resting location. Portable, battery-operated motion-sensing devices may be mounted on artworks or other objects that may sound an alarm if the object is moved. Other objects, such as computers, may be protected simply by chaining or otherwise securing them to a desk, table or other fixed structure with a tether, such as a Kensington® lock.
However, existing commercially available systems are not suitable for all uses. For example, it may not be desirable or cost-effective to erect protective cases around artworks. Many motion-based systems using lasers, infrared beams or other methodologies may be too costly or may be impractical for use in homes, offices, small galleries, and other locations. Moreover, in homes, offices, galleries, and some museums, it may be undesirable to keep people at a distance from artworks; it may be desirable to allow visitors or owners to appreciate the work from a close distance.
It also may be undesirable to mount a battery-operated device, such as a battery-powered motion detector, on some types of artworks. Regular replacement of the battery may subject the artwork to an undesirable degree of handling. Moreover, if the batteries were to leak, caustic chemicals seeping from the batteries may cause damage to the artwork to which the battery-powered device is mounted. For sculptures, fine pottery, or other small artworks or precious objects, it may be challenging to attach a battery-powered device to the object.
Finally, many existing systems may simply be aesthetically undesirable. Some devices designed to be attached to an artwork or designed to rest beneath or behind an artwork may detract from the enjoyment of the artwork it is designed to protect.
Thus, it would be desirable to protect an artwork or other valuable object from theft or damage by providing a way to detect movement of the artwork or valuable object indicative of possible theft or other undesired handling of the object, without the requirement of devices that are overly complex, costly, or bulky, that are aesthetically unappealing, or that pose a risk of damage to the artwork or other valuable object.

Sensor system for protection of artworks and other valuable objects


The present invention discloses an LED lamp comprising a base, a lamp body coupled to the base, a light emitting assembly arranged inside the lamp body, a positioning component fixed on the lamp body and defining a groove, a flexible component having a fixed end fixed to the lamp body and a free end, and a driver board defining a slot and electrically connected with the light emitting assembly, wherein the driver board is disposed in the groove and the free end of the flexible component is locked into the slot. A method for assembling the LED lamp is also described.

Compared with traditional incandescent lamps, LED lamps have many advantages, such as low power consumption, long service life, greater brightness, less heat emission, as well as being more environmentally friendly. LED lamps work by using LED chips as a source of light. In order for an LED chip to emit light normally, LED lamps usually use a driver to drive the LED chip. However, current LED lamp assembly techniques make the driver and other components of the LED lamps difficult to assemble.
Therefore, it is hoped to provide a new and improved LED lamp and assembling method thereof.


Provided is an organic EL illumination panel substrate, and a manufacturing method therefor, that improves the manufacturing efficiency and reduces the cost for an organic EL illumination panel substrate and that is capable of achieving an organic EL illumination panel with superior yields and reliability. The organic EL illumination panel substrate has a light transmitting substrate (11), a transparent electrode (12) and an auxiliary electrode (13). The transparent electrode (12) is arranged on one face of the light transmitting substrate (11). The auxiliary electrode (13) is electrically connected to the transparent electrode (12). On the light transmitting substrate (11), there is an insulating layer (14) at a position corresponding to an electrode lead-out section for an upper electrode of an organic EL layer that is disposed facing the transparent electrode (12) and that constitutes the organic EL illumination panel. There is a conductive layer between the light transmitting substrate (11) and the insulating layer (14).

In organic EL (electroluminescence) lighting panels used for organic EL lighting devices, generally, transparent electrodes formed of transparent conductive materials such as ITO, ZnO, SnO2 (NESA glass), and the like are used as electrodes at the side where the light is led out. Since the volume resistivities of the above-described transparent conductive materials are high, the sheet resistances become high in the case where the materials are used as thin films. Therefore, in an organic EL lighting panel using the above-described transparent electrode, a voltage drop due to increase in wiring resistance is caused as distanced from a transparent electrode end (feed terminal from power supply), i.e., as approached toward the inside (center) of the organic EL lighting panel. When the voltage drops at an electrode part, it causes an electric power loss at the electrode part as well as decreases in luminance and chromaticity, and thereby the luminance uniformity and chromaticity uniformity within a surface of an organic EL lighting panel are decreased. The above-described decreases in luminance and chromaticity are caused because an organic EL element is an electroluminescent type element, an electric field at the center of the element becomes smaller than that at the vicinity of a feed terminal because of a voltage drop, the injection efficiency of a carrier (hole/electron) is decreased, and the luminous efficiency is decreased.
Hence, for reducing the wiring resistance at the transparent electrode side, the provision of an auxiliary electrode on a transparent electrode has been considered (see, for example, Patent Documents 1 and 2). At this time, an end-insulating layer for covering the end of the transparent electrode is provided for avoiding the conduction between an upper electrode (in the case where the transparent electrode is an anode, a cathode) provided at the upper side relative to a translucent substrate and a transparent electrode, and an interlayer-insulating layer for covering the auxiliary electrode is provided for avoiding the conduction between the auxiliary electrode and an organic EL element (see, for example, Patent Document 2).
The organic EL lighting panel is manufactured, as shown in FIGS. 9A to C, by the following steps, for example. A translucent electrode material (for example, ITO) is laminated (formed) on a translucent substrate and the patterning using a photoresist is performed to form a translucent electrode layer. After removing the photoresist, an auxiliary electrode-forming material layer is formed, and an auxiliary electrode of a desired pattern is formed by a photolithography step or the like. Specifically, an auxiliary electrode-forming material layer is laminated all over a translucent substrate on which a translucent electrode layer is formed, a photoresist is applied thereto, the auxiliary electrode-forming material layer is formed into a desired pattern by an exposure through a mask on which a desired pattern is formed, a development, and an etching, and thereafter the resist on the auxiliary electrode-forming material layer is removed. Thereafter, an interlayer-insulating layer for covering the auxiliary electrode and an end-insulating layer for the end of the translucent electrode layer are each formed by a photolithography step in the same manner as described above. Then, an organic layer and an upper electrode layer are laminated thereon to manufacture an organic EL lighting panel.

Organic el lighting panel substrate, method for manufacturing organic el lighting panel substrate, organic el lighting panel, and organic el lighting device


A photocatalyst composite is provided which comprise a substrate having particles of a photocatalyst such as titanium oxide, adhered thereon via a less degradative adhesive such as a fluorinated polymer comprising a copolymer of a vinyl ester and/or vinyl ether and a fluoroolefin, or a silicon based polymer or cement. Furthermore, a process for producing the photocatalyst composite and a coating composition containing the photocatalyst composite are provided.

1. Field of the Invention
The present invention relates to a photocatalyst composite comprising a substrate having photocatalyst particles adhered thereon and a process for producing the same.
2. Description of Related Art
Exposure of photocatalyst particles to an irradiation of a wavelength corresponding to not less than the band gap energy causes the photoexcitation of electrons into a conduction band with a corresponding generation of holes in a valence band. The strong reduction power of the electrons and the strong oxidation power of the holes generated by this optical excitation have been utilized in decomposition and purification of organic materials as well as in decomposition of water. The photocatalyst particles to be used in such treatments are usually deposited on a substrate of dimensions larger than the photocatalyst particles in order to prevent them from scattering into the air or exhausting out of the system and subsequently to provide for easy separation of the photocatalyst from the treatment system. The deposition of photocatalyst particles on a substrate has been accomplished by a method comprising sintering the photocatalyst particles on the substrate at a temperature of 400xc2x0 C. or higher to adhere the particles to the substrate, or a method comprising spraying a precursor, which can be converted to photocatalyst through thermal decomposition, onto a substrate heated at a temperature of about 400xc2x0 C., thereby adhering the particles on the substrate. Alternatively, there has been proposed a method immobilizing photocatalyst particles using a certain type of fluorinated polymer. For example, Japanese Patent KOKAI (Laid-open) No. Hei 4-284851 discloses a method comprising laminating a mixture of photocatalyst particles and a fluorinated polymer and compressing the laminate under a pressure. Japanese Patent KOKAI (Laid-open) No. Hei 4-334552 discloses a method comprising thermally fusing a fluorinated polymer to adhere photocatalyst particles thereto.
Recently, an attempt has been made to use photocatalyst particles for decomposition of deleterious materials, malodorous materials and oily substances in the waste products produced daily in inhabitant circumstances as well as purification and sterilization of the waste products. Thus the photocatalyst particles have found ever broadening areas of application. In this regard, there is a need for a method capable of adhering firmly photocatalyst particles onto any substrate, which adhesion can be maintained over an extended period of time, without losing their photocatalytic function. Unfortunately, the prior art methods as described above suffer from insufficient adhesion strength as being susceptible to delamination under external pressure, and they require heating at high temperatures so that they can not apply to a substrate not resistant to heat such as plastics, interior materials such as office walls and the surfaces of various products which are difficult to heat, and the like. In addition, there are problems that the thermal treatments at high temperatures cause the photocatalyst particles to reduce their specific surface area resulting in a reduction in their photocatalytic function. Moreover, there may be required specific means such as devices for adhering under pressure, or fusing under heat.
One object of the present invention is to provide a photocatalyst composite comprising a substrate having photocatalyst particles adhered thereon via a less degradative adhesive.
Another object of the present invention is to provide a process for producing the photocatalyst composite.
A further object of the present invention is to provide a coating composition using the photocatalyst composite.

Photocatalyst composite and process for producing the same

Minamikosugaya Jutaku 2-506, 2000-10, Kosugayacho


A hand-held power tool includes a housing with a tool fitting for receiving an insertion tool, and at least one illuminating element for illuminating the working area of the hand-held power tool; wherein the at least one illuminating element is located in the region of the tool fitting.

The present invention relates to a hand-held power tool.
Hand-held power tools are made known in the related art that are equipped with a light-emitting diode so that work can be carried out with the hand-held power tool even in poorly-lit surroundings. To this end, the light-emitting diode is located at a suitable point on the hand-held power tool, and it is oriented such that it illuminates the working area. According to DE 102 54 829 A, for example, a hollow cylindrical lamp housing is integrally formed in a lower region of the motor housing, in which a lamp "chute" for accommodating a light-emitting diode is formed. The opening of the lamp housing points in the direction of the working area.
Known hand-held power tools with light-emitting diodes do not adequately illuminate the working area, however, since the light-emitting diode is located relatively far from the working area, due to its location on the hand-held power tool. In addition, with many hand-held power tools, the light-emitting diode illuminates the working area at an angle, e.g., from below or above. As a result, parts of the housing and/or the insertion tool cast a shadow on the working area.


A method implements a web application that designs components. The method includes configuring a network interactively by receiving a network selection, updating network selection options using the network selection, and presenting network view updated using the network selection. The method includes generating a component listing for at least a part of the network of the network and using the network selection. The method includes configuring a component from the component listing interactively by receiving a component selection, updating component selection options using the component selection, and presenting a component view updated using the component selection. The method includes presenting a schedule, for the component listing, generated by simulating assembly of components, including the component, of the component listing using a planning system.

Data centers use optical cables to connect networking equipment, including switches, routers, and servers. Different cables may use different lengths and connectors to connect the networking equipment. A challenge is to identify and enumerate the different components and configurations (cables, lengths, connectors, panels, modules, components, etc.) to assemble and connect the networking equipment.


A moulding material composition for use in sanitary appliances, such as plastic sinks, baths, or wash basins, having a polyester resin in a monomer liquid having a polymerizable vinyl group, a thermoplastic non-shrink polymer, an organic peroxide, glass fibers, a stripping agent of either calcium or zinc stearate; and a filler material. The filler material can be either chemically coated glass micro-beads or calcium carbonate in a marble crystalline form. The calcium carbonate can be provided with or without a pigment coating. In particular, the pigment can be of a polyurethane epoxy material.

Plastic material sanitary appliances are destined to replace traditional metal or ceramic sanitary appliances which have a high cost and a limited life.
The plastic material used today, comprising natural products, constitutes a composite mineral material. The manufactured product must therefore have high quality when applied, for instance, to a sink which must have a considerable impact resistance, since it is used with heavy and varied metal kitchen utensils. The surface of a sink should have abrasion resistance and mechanical strength.
Bearing in mind its environment, the sink must also remain extremely stable in contact with water and must not allow attack by the various domestic products. The material in use must also have good sound and thermal insulating properties.
Products now being manufactured show considerable disadvantages with regard to mechanical strength and stability in contact with water. The material in use does not allow products to be made in a perfectly uniform and an easily moulded manner at high temperature and under high pressure.
Materials are known based on thermosetting resin and mineral fillers, already used in the production of sanitary appliances. In the composition of known moulding materials, a non-saturated polyester-type resin is dissolved in a mixture of liquid monomers comprising, for instance, a vinyl group. A non-shrink thermoplastic is also known, which is active during the co-polymerization of the resin and of the monomer. An organic peroxide catalyst is also used to trigger the resin cross-linking.
It is also known for the compositions in use to utilize reinforcement fibers such as glass fibers, to ensure the rigidity of cross-linked material. Since these products are moulded at high temperature and under high pressure, a mould parting agent with known properties such as calcium and zinc stearate is utilized.
Fillers contained in the known resin are made up, more particularly, of silica and they do not include calcium carbonate.
It has been found that the use of calcium carbonate under certain conditions could, on the contrary, allow very good quality sanitary appliances to be obtained under certain conditions namely with a good resistance to abrasion and water.
If calcium carbonate in the form of marble with or without coating pigmentation is used, in combination with glass beads, it allows an unexpected effect to be achieved. This effect is the deterioration of fiberglass normally introduced to obtain the rigidity of cross-linked material.


Techniques for detecting temporal process variation and for managing and predicting performance of automatic classifiers applied to such processes using performance estimates based on temporal ordering of the samples are presented.

Many industrial applications that rely on pattern recognition and/or the classification of objects, such as automated manufacturing inspection or sorting systems, utilize supervised learning techniques. A supervised learning system, as represented in FIG. 1, is a system that utilizes a supervised learning algorithm 4 to create a trained classifier 6 based on a representative input set of labeled training data 2. Each member of the set of training data 2 consists of a vector of features, xi, and a label indicating the unique class, ci, to which the particular member belongs. Given a feature vector, x, the trained classifier, f, will return a corresponding class label, f(x)=ĉ. The goal of the supervised learning system 4 is to maximize the accuracy or related measures of the classifier 6, not on the training data 2, but rather on similarly obtained set(s) of testing data that are not made available to the learning algorithm 4. If the set of class labels for a particular application contains just two entries, the application is referred to as a binary (or two-class) classification problem. Binary classification problems are common in automated inspection, for example, where the goal is often to determine if manufactured items are good or bad. Multi-class problems are also encountered, for example, in sorting items into one or more sub-categories (e.g., fish by species, computer memory by speed, etc.). Supervised learning has been widely studied in statistical pattern recognition, and a variety of learning algorithms and methods for training classifiers and predicting performance of the trained classifier on unseen testing data are well known.
Referring again to FIG. 1, given a labeled training data set 2 (D={xi, ci}), a supervised learning algorithm 4 can be used to produce a trained classifier 6 (f(x)=ĉ). A risk or cost, αij, can be associated with mistakenly classifying a sample as belonging to class i when the true class is j. Traditionally, correct classification is assigned zero cost, αii=0. A typical goal is to estimate and minimize the expected loss, namely the weighted average of the costs the classifier 6 would be expected to incur on new samples drawn from the same process. The concept of loss is quite general. Setting αij=1 when i and j differ, and αii=0 when they are identical (so-called zero/one loss) is equivalent to treating all errors as equal and leads to minimization of the overall misclassification rate. More typically, different types of errors will have different associated costs. More complicated loss formulations are also possible. For example, the losses au can be functions rather than constants. In every case, however, some measure of predicted classifier performance is defined, and the goal is to maximize that performance, or, equivalently, to minimize loss.
There are several prior art techniques for predicting classifier performance. One such technique is to use independent training and testing data sets. A trained classifier is constructed using the training data, and then performance of the trained classifier is evaluated based on the independent testing data. In many applications, collection of labeled data is difficult and expensive, however, so it is desirable to use all available data during training to maximize accuracy of the resulting classifier.
Another prior art technique for predicting classifier performance known as "conventional k-fold cross-validation", or simply "k-fold cross-validation" avoids the need for separate testing data, allowing all available data to be used for training. In k-fold cross-validation, as illustrated in FIGS. 2A and 2B, the training data {xi, ci} are split at random into a k subsets, Di, 1≦i≦k, of approximately equal size (FIG. 2B, step 11). For iterations i=1 to k (steps 12-17), a supervised learning algorithm is used to train a classifier (step 14) using all the available data except Di. This trained classifier is then used to classify all the samples in subset Di (step 15), and the classified results are stored (step 16). In many cases, summary statistics can also be saved (at step 16) instead of individual classifications. With constant losses, for example, it suffices to save the total number of errors of various types. After k iterations, true (ci) and estimated (ĉi) class labels (or corresponding sufficient statistics) are known for the entire data set. Performance estimates such as misclassification rate, operating characteristic curves, or expected loss may then be computed (step 18). If the total number of samples is n, then the expected loss per sample can be estimated as ΣαĈiCi/n, for example. When k=n−1, k-fold cross-validation is also known as "leave-one-out cross-validation". A computationally more efficient variant known as "generalized cross-validation" may be preferred in some applications. Herein we refer to these and similar prior art techniques as "conventional cross validation" without differentiating between them.
In k-fold cross-validation, data samples are used to estimate performance only when they do not contribute to training of the classifier, resulting in a fair estimate of performance. Additionally, for large enough k, the training set size (approximately (k−1)/k·n, where n is the number of labeled training data samples) during each iteration above is only slightly less than that of the full data set, leading to only mildly pessimistic estimates of performance.
Many supervised learning algorithms lead to classifiers with one or more adjustable parameters controlling the operating point. For simplicity, discussion is herein restricted to binary classification problems, where ci is a member of one or the other of two different classes. However, it will be appreciated that the principles discussed herein may be extended to multiple-class classification problems. In a binary classification, a false positive is defined as mistakenly classifying a sample as belonging to the positive (or defect) class when it actually belongs to the negative (or good) class. Similarly, a true positive is defined as correctly classifying a sample as belonging to the positive class. False positive rate (also known as false alarm rate) may then be defined as the number of false positives divided by the number of members of the negative class. Similarly, sensitivity is defined as the number of true positives divided by the number of members of the positive class. With these definitions, performance of a binary classifier with an adjustable operating point can be summarized by an operating characteristic curve, sometimes called a receiver operating characteristic (ROC) curve, exemplified by FIG. 3. Varying the classifier operating point is equivalent to choosing a point lying on the ROC curve. At each operating point, estimates of the rates at which misclassifications of either type occurs are known. If the associated costs, αij, are also known, an expected loss can be computed for any operating point. For monotonic operating characteristics, a unique operating point that minimizes expected loss can be chosen. As noted above, k-fold cross-validation provides the information required to construct an estimated ROC curve for binary classifiers.
In addition to making effective use of all available data, k-fold cross-validation has the additional advantage that it also allows estimating reliability of the predicted performance. The k-fold cross-validation algorithm can be repeated with a different pseudo-random segregation of the data into the k subsets. This approach can be used, for example, to compute not just the expected loss, but also the standard deviation of this estimate. Similarly, non-parametric hypothesis testing can be performed (for example, k-fold cross-validation can be used to answer questions such as "how likely is the loss to exceed twice the estimated value?").
Prior art methods for predicting classifier performance assume that the set of training data is representative. If it is not, and in particular if the process giving rise to the training data samples is characterized by temporal variation (e.g., the process drifts or changes with time), then the trained classifier may perform much more poorly than predicted. Such discrepancies or changes in performance can be used to detect temporal variation when it occurs, but it would be preferable to detect temporal variation in the process during the training phase. Supervised learning does not typically address this problem.
Two techniques that do explicitly deal with the prediction of temporal variation in a process are time series analysis and statistical process control. Time series analysis attempts to understand and model temporal variations in a data set, typically with the goal of either predicting behavior for some period into the future, or correcting for seasonal or other variations. Statistical process control (SPC) provides techniques to keep a process operating within acceptable limits and for raising alarms when unable to do so. Ideally, statistical process control could be used to keep a process at or near its optimal operating point, almost eliminating poor classifier performance due to temporal variation in the underlying process. In practice, this ideal is rarely approached because of the time, cost, and difficulty involved. As a result, temporal variation may exist within predefined limits even in well controlled processes, and this variation may be sufficient to interfere with the performance of a classifier created using supervised learning. Neither time series analysis nor statistical process control provides tools directly applicable for analysis and management of such classifiers in the presence of temporal process variation.
Prior art methods for predicting classifier performance are applicable when either a) the underlying process which generated the set of training data has no significant temporal variation, or b) temporal variation is present, but the underlying process is stationary and ergodic, and samples are collected over a long enough period that they are representative. In many cases where there is explicit or implicit temporal variation in the underlying process the assumption that the set of training data is representative of the underlying process is not justified, and k-fold cross-validation can dramatically overestimate performance. Consider, for example, the processes illustrated in FIGS. 4A, 4B, and 4C. "State" in these figures is meant only for purposes of illustration. The actual state will be of high, often unknown dimension and is itself rarely known. The process illustrated in FIG. 4A has no temporal variation. The process illustrated in FIG. 4B is a stationary process with random, ergodic fluctuations. The process illustrated in FIG. 4C shows steady drift accompanied by random fluctuations about the local mean. Conventional k-fold cross-validation will correctly predict classifier performance for the process illustrated in FIG. 4A given sufficient training data. For the process illustrated in FIG. 4B, correct results will also be attained if the data set is collected over a sufficiently long period so that states are sampled with approximately the equilibrium distribution. Failing this, performance will typically be overestimated. For the process illustrated in FIG. 4C, actual performance may match predicted performance initially, but will degrade as points further into the future are sampled. This list of sample processes is for purposes of illustration only and is by no means exhaustive.
The determination of whether the set of training data is representative of the process often requires the collection of additional labeled training data, which can be prohibitively expensive. As an example, consider fabrication of complex printed circuit assemblies. Using SPC, individual solder joints on such printed circuit assemblies may be formed with high reliability, e.g. with defect rates on the order of 100 parts-per-million (ppm). Defective joints may therefore be quite rare. Large printed circuit assemblies can exceed 50,000 joints, however, so the economic impact of defects would be enormous without the ability to automatically detect joints that are in need of repair. Supervised learning is often used to construct classifiers for this application. Thousands of defects are desirable for training, but since good joints outnumber bad joints by 10,000 to 1, millions of good joints must be examined in order to obtain sufficient defect samples for training the classifier. This poses a significant burden on the analyzer (typically a human expert) tasked with assigning true class labels, so collection of training data is time-consuming, expensive, and error prone. In addition, the collection of more training data than necessary slows the training process without improving performance. Accordingly, it is desirable to use the smallest training data set possible that yields the desired performance.
For the reasons described above, it would be desirable to be able to detect the presence or possible presence of temporal variation in the process from indications in the training data itself. It would be further desirable to be able to predict expected future classifier performance even in the presence of temporal variation in the underlying process. Finally, it would be useful to project the performance gain likely to result from collection of additional training data, and for exploring various options for its use (for example, to answer the question of whether it would be better to simply add to the existing training data or to periodically retrain the classifier based on a sliding window of training data samples).

Methods and apparatus for detecting temporal process variation and for managing and predicting performance of automatic classifiers


A broadband wireless access (BWA) communication system including a serving BS for servicing an SS in at least one of a plurality of sub-carrier frequency bands, and a plurality of neighbor BSs adjacent to the serving BS. The SS measures CINRs of frequency band signals from the neighbor BSs, requests a handoff for a target BS having the highest CINR to the serving BS, transitions to the frequency band of the target BS, and acquires synchronization to the target BS. The SS transmits ranging information to the target BS in a ranging information region assigned by the target BS, receives from the target BS connection ID information between the target BS and the SS, transmits a handoff registration request message to the target BS according to the connection ID information, and receives a response message for the handoff registration request message from the target BS.

1. Field of the Invention
The present invention relates generally to a broadband wireless access (BWA) communication system, and in particular, to a system and method for implementing a handoff as determined by a subscriber station (SS) in a traffic state in a BWA communication system using OFDM (Orthogonal Frequency Division Multiplexing).
2. Description of the Related Art
Currently, a number of studies are being conducted on providing of services with diverse QoSs (Qualities of Service) at or above about 100 Mbps to users in a next generation mobile communication system, i.e., a 4th (4G) generation communication system. The existing 3G communication systems support about 384 Kbps in an outdoor channel environment that is relatively poor and up to 2 Mbps in an indoor channel environment that is relatively good. Wireless LAN (Local Area Network) systems and wireless MAN (Metropolitan Area Network) systems generally support 20 to 50 Mbps. In this context, a new communication system is being developed by guaranteeing mobility and QoS to the wireless LAN and MAN systems supporting relatively high data rates, thereby supporting high-speed services intended in the 4G communication system.
Despite its feasibility for high-speed communication service due to a wide coverage area and a high data rate, the wireless LAN systems have no provisions for the mobility of an SS or a handoff caused by fast movement of the SS (i.e., cell selection). A communication system based on IEEE (Institute of Electrical and Electronics Engineers) 802.16a communicates through ranging between an SS and a base station (BS). This system will be described with reference to FIG. 1.
FIG. 1 schematically illustrates a conventional OFDM/OFDM-based BWA communication system, particularly an IEEE 802.16a/IEEE 802.16e communication system. However, before describing FIG. 1, it is important to address how the IEEE 802.16a/IEEE 802.16e communication system was developed. The wireless MAN system is a kind of BWA communication system. As compared to the wireless LAN system, it offers wider coverage and supports higher data rates. OFDM and OFDMA (Orthogonal Frequency Division Multiplexing Access) were introduced to the physical channel of the wireless MAN system to support a broadband transmission network. This system is the IEEE 802.16a communication system. The application of OFDM/OFDMA to the wireless MAN system enables the IEEE 802.16a communication system to transmit a physical channel signal over a plurality of sub-carriers, for high-speed data transmission. The IEEE 802.16e communication system, which is an extension of IEEE. 802.16a, introduces nomadic capabilities (mobility of SS). However, the IEEE 802.16e communication system is yet to be specified.
Referring to FIG. 1, the IEEE 802.16a/IEEE 802.16e communication system is configured in a single cell architecture. It comprises a BS 100 and a plurality of SSs 110, 120, and 130 covered by the BS 100. Signal transmission/reception between the BS and the SSs 110, 120, and 130 is performed in OFDM/OFDMA.
FIG. 2 schematically illustrates a downlink frame in the conventional OFDM/OFDM-based BWA communication system, particularly the downlink frame of the IEEE 802.16a/IEEE 802.16e communication system. Referring to FIG. 2, the downlink frame includes a Preamble 200, a Broadcast Control 210, and a plurality of TDM (Time Division Multiplex) fields 220 and 230. The Preamble 200 delivers a synchronization signal, namely a preamble sequence for synchronizing a BS and an SS. The Broadcast Control 210 contains a DL (Downlink)_MAP 211 and a UL (Uplink)_MAP 213. The DL_MAP 211 delivers a DL_MAP message, which includes the information elements (IEs) as shown below in Table 1.
TABLE 1SyntaxSizeNotesDL-MAP_Message_Format( ) { Management Message Type = 2 8 bits PHY Synchronization FieldVariableSee appropriate PHY specification. DCD Count 8 bits Base Station ID48 bits Number of DL-MAP Elements n16 bits Begin PHY Specific Section {See applicable PHY section.  for(i=1; i<=n; i++) {For each DL-MAP element 1 to n.   DL_MAP_Information_Element( )VariableSee corresponding PHY specification.   if!(byte boundary) {    Padding Nibble 4 bitsPadding to reach byte boundary.   }  } }}
In Table 1, Management Message Type indicates the type of the transmitted message, PHY (PHYsical) Synchronization is set according to the modulation/demodulation of the physical channel, for synchronization acquisition, DCD (Downlink Channel Descript) Count is the number of changes in the configuration of a DCD message containing a downlink burst profile, Base Station ID (Identifier) identifies a BS, and Number of DL_MAP Elements n indicates the number of elements following Base Station ID. Although not shown in Table 1, the DL_MAP message further includes information about ranging codes assigned to respective ranging types as will described later in more detail.
The UL_MAP 213 delivers a UL_MAP message includes IEs as shown below in Table 2.
TABLE 2SyntaxSizeUL_MAP_Message_Format( ) { Management Message Type=3 8 bits Uplink channel ID 8 bits UCD Count 8 bits Number of UL_MAP Elements n16 bits Allocation Start Time32 bits Begin PHY Specific Section {  for(i=1; i<n; i+n)   UL_MAP_Information_Element {Variable     Connection ID     UIUC      Offset    }  } }}
In Table 2, Management Message Type indicates the type of the transmitted message, Uplink Channel ID identifies the uplink channel used, UCD (Uplink Channel Descript) Count is the number of changes in the configuration of a UCD message containing an uplink burst profile, and Number of UL_MAP Elements n indicates the number of elements following UCD Count. The Uplink Channel ID is assigned only in a MAC (Media Access Control) sub-layer.
An UIUC (Uplink Interval Usage Code) indicates the usage of an offset set in Offset. For example, if the UIUC is 2, this indicates that a starting offset for initial ranging is set in the Offset. If the UIUC is 3, this indicates that a starting offset for bandwidth request ranging (BW-request ranging) or maintenance ranging (periodic ranging) is set in the Offset. As described above, the Offset indicates the starting offset for initial ranging, BW-request ranging, or periodic ranging according to the information in the UIUC. Information about the feature of a physical channel that delivers the UIUC is provided in the UCD.
If an SS has failed in ranging, it determines a backoff value to increase success probability at a next attempt and retries the ranging after a time delay corresponding to the backoff value. Information needed to determine the backoff value is also provided by the UCD message. The structure of the UCD message will be detailed with reference to Table 3 below.
TABLE 3SyntaxSizeNotesUCD-Message_Format( ) { Management Message Type = 08 bits Uplink channel ID8 bits Configuration Change Count8 bits Mini-slot size8 bits Ranging Backoff Start8 bits Ranging Backoff End8 bits Request Backoff Start8 bits Request Backoff End8 bits TLV Encoded Information for the overall channelVariable Begin PHY Specific Section {  for(i=1; i<n; i+n)   Uplink_Burst_DescriptorVariable  } }}
In Table 3, a Management Message Type indicates the type of the transmitted message, an Uplink Channel ID identifies the uplink channel used, a Configuration Change Count is the number of configuration changes counted by a BS, a Mini-slot Size indicates the size of an uplink physical channel mini-slot, a Ranging Backoff Start indicates the starting point of an initial ranging backoff, that is, the size of an initial backoff window for initial ranging, a Ranging Backoff End indicates the end point of the initial ranging backoff, that is, the size of a final backoff window for the initial ranging, a Request Backoff Start indicates the starting point of a backoff for contention data and requests, that is, the size of an initial backoff window for contention data and requests, and a Request Backoff End indicates the end point of the backoff for contention data and requests, that is, the size of a final backoff window for contention data and requests. The backoff is defined as a time delay value by which the SS waits for a ranging retry, if it fails in any rangings, which will be described in more detail herein below The BS transmits the backoff to the SS. For example, if the Ranging Backoff Start and Ranging Backoff End indicate "10", the SS attempts the next ranging after a time delay equivalent to 210 (1024) ranging tries.
The TDM fields 220 and 230 correspond to time slots assigned to SSs in TDMA (Time Division Multiple Access). The BS broadcasts necessary information to SSs within its coverage area in the DL_MAP 211 of the downlink frame. Upon a power-on, each of the SSs monitors all frequency bands set for it and detects the strongest pilot channel signal, that is, a pilot channel signal having a highest CINR (Carrier to Interference Noise Ratio). A BS that transmits the highest CINR-pilot channel signal is designated by the SS as its serving BS. Additionally, the SS attains control information about its uplink and the downlink and information about the positions of actual transmit/receive data by checking the DL_MAP 211 and the UL_MAP 231.
FIG. 3 schematically illustrates an uplink frame in the conventional OFDM/OFDMA-based BWA communication system, particularly the IEEE 802.16a/IEEE 802.16e communication system. However, before describing FIG. 3, ranging types, that is, initial ranging, periodic ranging, and BW-request ranging, as provided by the IEEE 802.16a/IEEE 802.16e communication system will be described.
A. Initial Ranging
Initial ranging is performed upon a request from the BS to synchronize with the SS. The purposes of the initial ranging are accurate acquisition of a time offset and adjustment of transmit power between the SS and the BS. Upon a power-on, the SS synchronizes with the BS by receiving a DL_MAP message and a UL_MAP/UCD message, and performs initial ranging to adjust the time offset and transmit power with the BS. Because the OFDM/OFDMA in the IEEE 802.16a/IEEE 802.16e communication system is used, the ranging procedure requires ranging sub-channels and ranging codes. The BS assigns available ranging codes according to the usage, that is, type of ranging.
The ranging codes are generated by segmenting a PN (Pseudorandom Noise) sequence of, for example, (215−1) bits in length in predetermined units. In general, two 53-bit ranging sub-channels form one ranging channel and the ranging codes are produced by segmenting the PN code by the 106-bit ranging channel. Up to 48 ranging codes (RC#1 to RC#48) as constructed in this manner can be assigned to SSs. For each SS, at least two ranging codes as a default are applied to the three types of rangings, i.e., initial ranging, periodic ranging, and BW-request ranging. Thus, different ranging codes are assigned to the three ranging types. For example, N ranging codes are assigned for initial ranging, M ranging codes for periodic ranging, and L ranging codes for BW-request ranging. The SSs are notified of ranging codes assigned to them by the DL_MAP message and perform ranging procedures using the ranging codes in compliance of their usages.
B. Periodic Ranging
After adjusting the time offset and transmit power with the BS by the initial ranging, the SS performs periodic ranging to adjust a channel state with the BS. For the periodic ranging, the SS uses ranging codes assigned for the periodic ranging.
C. BW-Request Ranging
After adjusting the time offset and transmit power with the BS by the initial ranging, the SS requests a bandwidth by ranging, for actual communication with the BS.
Referring to FIG. 3, an uplink frame comprises Initial Maintenance Opportunities 300 for initial ranging and periodic ranging, Request Contention Opportunities 310 for BW-request ranging, and SS Scheduled Data fields 320 including uplink data. The Initial Maintenance Opportunities 300 includes a plurality of access bursts for initial ranging and periodic ranging, and a collision period produced when a collision occurs between the access bursts. The Request Contention Opportunities 310 includes a plurality of bandwidth requests for bandwidth request ranging, and a collision period produced when a collision occurs between the bandwidth requests. The SS Scheduled Data fields 320 include SS1 Scheduled Data to SS N Scheduled Data. An SS transition gap exists between adjacent SS Scheduled Data fields.
FIG. 4 is a flowchart illustrating a ranging procedure between an SS and a BS in the conventional OFDM-based BWA communication system. Referring to FIG. 4, upon a power-on, an SS 400 monitors all predetermined frequency bands and detects a pilot channel signal with a highest CINR. Considering a BS 420 that transmits the detected pilot channel signal as a serving BS, the SS 400 acquires system synchronization with the BS 420 by receiving the preamble of a downlink frame from the BS 420.
As described above, with the system synchronization acquired, the BS 420 transmits DL_MAP and UL_MAP messages to the SS 400 in steps 411 and 413. As illustrated in Table 1, the DL_MAP message provides information needed for the SS 400 to synchronize with the BS 420, and information about the configuration of a physical channel that delivers messages to the SS 400 on the downlink after synchronizing. As illustrated in Table 2, the UL_MAP message provides the SS 400 with information about a scheduling period for the SS 400 and the configuration of an uplink channel.
The BS 420 periodically broadcasts the DL_MAP message to all SSs. When the SS 400 is capable of receiving the DL_MAP message continuously, it is said that the SS 400 is synchronized to the BS 420. That is, SSs, which have received the DL_MAP message, can receive all downlink messages.
As illustrated in Table 3, the BS 420 transmits to the SS 400 a UCD message containing information about a backoff value in case of access failure.
For ranging, the SS 400 transmits a Ranging. Request (RNG_REQ) message to the BS 420 in step 415. In step 417, the BS 420 then transmits to the SS 400 a Ranging Response (RNG_RSP) message containing information required to adjust frequency, time offset, and transmit power.
The RNG_REQ message is formatted as illustrated in Table 4 below.
TABLE 4SyntaxSizeNotesRNG-REQ_Message_Format( ) { Management Message Type = 48 bits Downlink Channel ID8 bits Pending Until Complete8 bits TLV Encoded InformationVariableTLV specific}
In Table 4, a Downlink Channel ID indicates the ID of the downlink channel that has delivered the UCD message to the SS 400. Pending Until Complete indicates the priority level of an RNG_RSP message for the RNG_REQ message. If the Pending Until Complete is 0, a previous RNG_RSP has higher priority. If the Pending Until Complete is not 0, an RNG_RSP for the current RNG_REQ has priority over an RNG_RSP for any other RNG_REQ.
The RNG_RSP message in response for the RNG_REQ message illustrated in Table 4 is formatted as illustrated in Table 5 below.
TABLE 5SyntaxSizeNotesRNG-RSP_Message_Format( ) { Management Message Type = 58 bits Uplink Channel ID8 bits TLV Encoded InformationVariableTLV specific}
In Table 5, an Uplink Channel ID is the ID of the uplink channel that has delivered the RNG_REQ message.
Herein below, a ranging procedure in an OFDMA-based IEEE 802.16e communication system will be described below. In the OFDMA-based IEEE 802.16e communication system, instead of transmitting the RNG_REQ message, a dedicated region for ranging is set and a ranging code is transmitted in the dedicated region, to thereby perform the ranging more efficiently.
FIG. 5 is a flowchart illustrating a ranging procedure between an SS and a BS in the conventional OFDMA-based BWA communication system. Referring to FIG. 5, upon a power-on, a BS 520 transmits DL_MAP and UL_MAP messages to an SS 500 in steps 511 and 513, respectively. Steps 511 and 513 are performed in the same manner as steps 411 and 413 of FIG. 4. Thus, they are not detailed here. Instead of transmitting the RNG_REQ message as illustrated in FIG. 4, the SS 500 transmits a ranging code to the BS 520 in step 515. The BS 520 transmits an RNG_RSP message for the ranging code to the SS 500 in step 517.
In relation to the ranging code, the RNG_RSP message further includes the following:
1. Ranging Code: a received ranging CDMA code;
2. Ranging Symbol: the OFDM symbol in which the ranging CDMA code was received;
3. Ranging Sub-channel: the ranging sub-channel in which the ranging CDMA code was received; and
4. Ranging Frame Number: the frame number in which the ranging CDMA code was received.
As described above, the IEEE 802.16a communication system works for fixed SSs in a single cell structure with no regard to the mobility of the SSs. Further, the IEEE 802.16e communication system adds SSs' mobility to the IEEE 802.16a communication system. Therefore, it must support the mobility in a multi-cell environment. To do so, the operations of the SS and the BS must be modified. However, no specific proposals have been made for the multi-cell and the SSs' mobility for the IEEE 802.16e communication system. Therefore, there is a pressing need for providing a handoff for an SS under a multi-cell environment in order to support the mobility of the SS in the IEEE 802.16e communication system.

System and method for implementing a handoff in a traffic state in a broadband wireless access communication system


A picture display device having a vacuum envelope which is provided with a transparent face plate and a display screen having a pattern of luminescent pixels, and with a rear wall, comprising electron-producing means, an addressing system arranged between said means and the face plate so as to address desired pixels, and, adjacent to the display screen, a plate of electrically insulating material provided with apertures for passing electrons, in operation a voltage difference being applied across said plate, characterized in that the surface at the electron entrance side of the apertured plate is coated with a coating of a material selected from the group comprising nonstoichiometric nitrides, borides and carbides of Al and/or Si, and amorphous Si.

The invention relates to a picture display device having a vacuum envelope which is provided with a transparent face plate and a display screen having a pattern of luminescent pixels, and with a rear wall, comprising electron-producing means, an addressing system arranged between said means and the face plate so as to address desired pixels, and, adjacent to the display screen, a plate of electrically insulating material provided with apertures for passing electrons.
The display device described above is of the thin-panel type. Display devices of the thin-panel type are devices having a transparent face plate and, arranged at a small distance therefrom, a rear plate, while a (for example, hexagonal) pattern of phosphor dots is provided on the inner surface of a face plate. If (video information-controlled) electrons impinge upon the luminescent screen, a visual image is formed which is visible via the front side of the face plate. The face plate may be flat or, if desired, curved (for example spherical or cylindrical).
A thin-panel display device described in U.S. Pat. No. 5,313,136 (=PHN 12.927) comprises a plurality of juxtaposed sources for emitting electrons, local electron propagation means cooperating with the sources, each having a wall of a high-ohmic, electrically substantially insulating material having a secondary emission coefficient which is suitable for propagating emitted electrons, and an addressing system comprising electrodes (selection electrodes) which can be driven row by row so as to extract electrons from the propagation means at predetermined extraction locations facing the luminescent screen, while further means are provided for directing extracted electrons towards pixels of the luminescent screen for producing a picture composed of pixels.
Other display devices of the thin-panel type to which the invention pertains are, for example, plasma displays and, in particular, field emission displays.
The luminescent screen is also referred to as the phosphor screen. An important component of the above-mentioned display device is an apertured plate of electrically insulating material, in many applications described as "the screen spacer".
The screen spacer is adjacent to the phosphor screen. Due to the efficiency and the saturation behaviour of the phosphor, it is of crucial importance that the acceleration voltage to the phosphor screen is as high as possible. Dependent on the phosphors used, 3 kV or, more frequently, 4 to 5 kV is a minimum requirement.
The screen spacer is made of an insulating material, particularly glass. The face plate is provided with a low-ohmic transparent conducting electrode of, for example ITO. This coating is provided with the phosphor screen and (possibly) a black matrix. A typical thickness of the screen spacer is 0.3 or 0.4 to 1.0 mm. The voltage difference between the input side of the screen spacer and the ITO coating should be as high as possible. At large voltage differences a number of unwanted effects in the form of picture errors may occur. The invention is based on the recognition that these effects are related to the "vacuum current" flowing through the screen spacer. The invention provides a display device of the type described in the opening paragraph, having surfaces, particularly at the electron entrance side of the screen spacer, treated in such a way that the occurrence of these unwanted effects (which, according to the invention, are based on secondary emission of electrons backscattered from the display screen at voltage differences of at least 5 kV across the spacer) are obviated entirely or partly. For this purpose, a coating is preferably used which has such a composition that its properties are stable under electron bombardment. This contributes to the lifetime.
To this end, an embodiment of a display device of the type described in the opening paragraph is characterized in that the surface at the entrance side of the apertured plate is coated with a coating of a material selected from the group comprising nonstoichiometric nitrides, borides and carbides of Al and/or Si, and amorphous Si, optionally doped with N and/or H.
It has been found that with the above coatings, which were found to be stable under electron bombardment, electrical resistances between 10.sup.10 .OMEGA./.quadrature. and 10.sup.14 .OMEGA./.quadrature. can be realized, which values are eminently suitable for the purpose of the invention, values between 10.sup.10 .OMEGA./.quadrature. and 10.sup.13 .OMEGA./.quadrature., and in particular 10.sup.11 to 10.sup.12 .OMEGA./.quadrature., being preferred. Of the above materials SiN.sub.x (0<x.ltoreq.1.3) is very well suited for an industrial process. Suitable resistance values are obtained in particular if 0<x.ltoreq.0.4.
It appears that at higher acceleration voltages, the unwanted effects leading to picture errors can effectively be prevented when these coatings are used. Further the resistance of the material of the apertured plate should be sufficiently high. This resistance R (in .OMEGA. cm) preferably satisfies logR.gtoreq.12.
The required coatings may be provided by means of plasma CVD or, preferably, (rf or dc) magnetron sputtering. Generally, the surface of the plate and the walls of the apertures are coated therewith, while leaving the choice of coating at one or two sides.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.


A preparation method of a gate electrode for semiconductor device which comprises forming a plurality of specific resist layers sensitive to an electron beam over a substrate through a silicon nitride film, subjecting the resist layers to an electron beam lithography to obtain an opening having a specific configuration at the opening portion, etching the silicon nitride film through the opening to form an opening in the silicon nitride film, etching the substrate through the opening of the silicon nitride film to form a cavity in the substrate, and forming a metal member on the substrate in the cavity in accordance with a metal-deposition and lift-off process to obtain the gate electrode in a projected shape.

1. Field of the Invention
The invention relates to a preparation method for an electrode and more particularly to a method suitable for the preparation of gate electrodes in various semiconductor devices.
2. Description of the Related Art
GaAs-MESFET or AlGaAs/GaAs-HEMT devices, which have conventionally been applied as a low noise amplifier for satellite broadcasting and communications in microwave band, are required to have lower parasitic capacitance by reducing gate lengths in order to improve their low noise amplification property.
Quartermicron gate electrodes are typically fabricated by lift-off process in the following manner to which FIG. 4 is referred. First, a silicon nitride film 12 and a resist film 13 are formed in this order on a GaAs substrate 11. A gate pattern is formed on the resist film 13 by electron beam lithography and used as a mask to open a hole in the silicon nitride film 12 which is then used as a mask to form a cavity 14 in the GaAs substrate 11. Thereafter, a metal deposition is conducted from the side of the silicon nitride film 12 and then the resist film 13 is removed by use of an organic solvent, leaving the deposited metal in the cavity on a corresponding portion of the substrate to the gate pattern to form a gate electrode 15. Reference numeral 16 designates the metal layer before the removal.
In the conventional preparation method for gate electrodes by the lift-off process using the resist film, the more the gate pattern is to be subminiaturized, the more the deposited metal 16 quickly closes up the hole of the resist film as already shown in FIG. 4, so that the resultant gate electrode is relatively smaller in height with respect to the gate length (a width of the contacting portion of the gate electrode with the substrate), resulting in the problem that devices with the resultant gate electrode are poor in their properties due to increased gate resistance based on the reduced gate length.
The invention has been designed to overcome the above problem. An object of the invention is to provide a preparation method for gate electrode which allows the height of the gate electrode formed to be enlarged with respect to gate length and, in other words, enables the gate electrode to be prepared with reduced gate length without causing increase of gate resistance.
The inventor has made earnest study to reduce the gate length without causing increase of gate resistance and found that the reason of the gate electrode not being prepared with larger height is due to that the opening of the resist layer has such a cross-sectional shape as extending almost vertically or being reversely tapered toward the outer area from which a metal vapour is supplied under the metal deposition, so that the deposited metal is caused to quickly close up the hole of thee resist layer immediately after start of the deposition. The inventor also found that when the hole of the resist layer has such a cross-sectional shape as being normally tapered toward the outer area, it takes longer time for the deposited metal to close up the hole of the resist layer to thereby allow quartermicron gate electrode to be deposited with larger height.
However, in the case of fabrication by using a conventional resist film of single layer type, electron beam lithography is hard to provide the hole of the resist film with the cross-sectional shape as being normally tapered as aforesaid.

Method for preparing electrode for semiconductor device


A sliding assisting device assists a movable body to move between a drawn-in position and a drawn-out position relative a main body. The sliding assisting device includes a unit main body provided on one of the main body and the movable body, and having a slider, a lock member, and a spring member; and an operating member provided on the other of the main body and the movable body. When the movable body is drawn out to a mid-course position from the drawn-in position or drawn-out position, the operating member displaces the lock member from a locked position to an unlocked position, so that the movable body slides from the mid-course position to the drawn-out position or drawn-in position by the spring member.

The present invention relates to a sliding assisting device for assisting a movable body such as a drawer and a lid to slide relative to a main body between a drawn-in position and a drawn-out position.
In a structure in which a movable body is switched to slide between a drawn-in position and a drawn-out position relative to a main body, when all the sliding operations to a drawn-in position and a drawn-out position are performed manually, it may cause fatigue and lack high quality. Accordingly, as disclosed in Patent Document 1, a movable body is urged to slide automatically in one direction toward the drawn-out position or the drawn-in position.
FIGS. 10(a) and 10(b) show a drawer apparatus disclosed-in Patent Document 1. FIG. 10(a) shows a drawn-in position of a movable body (not shown), and FIG. 10(b) shows a drawn-out position. Reference numeral 50 is a sidewall of the main body, reference numeral 55 is a drive pin formed on the movable body, reference numeral 60 is a tilting part placed between the main body sidewall and the movable body, and reference numeral 65 is a spring member. A guide track 51 is provided in the main body sidewall 50. The guide track 51 has a straight part 51a extending horizontally in a front-to-back direction, and a bow-shaped part 51b on a front side (right side in the drawing). The tilting part 60 has a slot 61 opening upwardly and a diagonal sidewall 62 extending from a front side of the slot 61. Bolts 63 engage in the guide track 51.
The spring member 65 accumulates a force in a process of sliding the movable body from the drawn-in position to the drawn-out position. One end of the spring member 65 is fixed on the main body, and the other end is fixed on the tilting part 60. The movable body is built into the main body in a state in which the drive pin 55 engages the slot 61.
When the movable body slides from the drawn-in position to the drawn-out position, the tilting part 60 moves along the straight part 51a of the guide track 51, and then is tilted forward at the bow-shaped part 51b. The drive pin 55 also moves from the slot 61 to a diagonal sidewall 62. Accordingly, the movable body is locked in the drawn-out position against the force of the spring member 65. When the movable body is pushed backward, the drive pin 55 returns from the diagonal wall part 62 to the slot 61, so that the movable body is drawn in with the force accumulated in the spring member 65. In Patent Document 1, the movable body slides to the drawn-in position with the force of the spring member 65, so that the movable body does not bounce back and is not drawn out again even when the movable body is strongly drawn in.
Patent Document 1: Japanese Patent Publication (Kokoku) No. 05-023763
In the conventional structure, the movable body slides automatically almost entirely from the drawn-out position to the drawn-in position. However, it is necessary to provide the strong pulling force to move the movable body from the drawn-in position to the drawn-out position, thereby deteriorating convenience. The drive pin 55 moves out from the slot 61 with a front slope of the tilting member 60 and engages the diagonal sidewall 62 as the lock mechanism for locking the movable body against the force of the spring member 65. Accordingly, it is difficult to strongly lock the movable body, thereby releasing the movable body by vibrations and the like.
When the movable body (drive pin 55) is draw out, an opening of the slot 61 provided in the tilting member 60 receives a large load accompanying the accumulation of the force of the spring member 65. Accordingly, it is desirable that the drive pin 55 enters deep in the opening. However, it is also necessary to easily release the drive pin 55 accompanying forward tilting of the tilting member 60, thereby limiting the opening. The conventional structure does not have an apparatus for assisting both operations of sliding the movable body toward the drawn-in position and toward the drawn-out position, thereby limiting the operation.
In view of the problems described above, a purpose of the present invention is to provide a sliding assisting device with a comparatively simple structure, thereby improving convenience and quality.
Further objects and advantages of the invention will be apparent from the following description of the invention.


A system, method and apparatus for locating a mobile communication device are provided. A data set is received, the data set comprising strengths of signals received at the mobile communication device from a plurality of wireless access points. The data set further comprises identifiers of wireless access points from which each signal was received. Scaled signal strengths are determined from the strengths of signals. The scaled signal strengths are compared with a record of signal strengths of wireless access points at given locations. Based on the comparing, a location of the mobile communication device is determined.

Presence data generally isn't real-time and its accuracy is lacking. For example, instant messaging applications, such as MSN messenger, simply sets a user's status to away if no keyboard/mouse interaction is detected in a certain timeframe. Although this information is useful under some circumstances, it fails to address the simple case where the user is reading a paper document at his/her desk. Another example would be presence systems which rely on calendar entries: even though a user is scheduled for a meeting in a specific room, there is no guarantee that he/she is actually there. This meeting may have been missed, double-booked etc.
Determination of presence on a more granular scale has been addressed in the past through schemes for determining the actual real-time location of a person. However many of such schemes are not cost effective and require specific hardware, for example RFID tags carried by individuals, with readers positioned at building entrances and/or throughout a building, costly GPS systems and the like. Further, WiFi (802.11x) systems may include tracking/triangulation schemes using specialized access points and triangulation software and/or specialized WiFi (802.11x) fingerprinting using hardware integrated into the access points, for example a Cisco Wireless Location Appliance from Cisco Systems 170 West Tasman Drive San Jose, Calif. 95134. However the use of such specialized access points adds cost and involves significant infrastructure changes to existing systems.
U.S. Pat. No. 7,149,531 to Pauli Misikangas discloses a system which addresses this problem by using the signal strengths of base stations in a wireless local-area network (WLAN) as measured by a given wireless device, to develop a probabilistic model of indicating a probability distribution for signal values of several base stations at several locations, and further using the probabilistic model and signal values at a radio interface to determine the location of the given wireless device at a later time. However, calibration of the system is specific to a particular wireless device, and if the location of another type of wireless device is to be determined, the system must be recalibrated using the other type of wireless device.
A similar approach is disclosed in "Locus: Wireless LAN Location Sensing" by Arvinder Singh and Ali Taheri, in Project Report submitted to the Worcester Polytechnic Institute and dated Jan. 19, 2004 ("Locus"). The system of locus involves recording the signal strengths of several visible wireless access points for a given number of known coordinates, for example in a building. To then later find a location of a wireless device communicating with the access points, the observed signal strengths of the access points are compared against the stored values and the closest match results in a location approximation. However, Locus is prone to false signature matches, or no match at all, as matching is performed on a per value basis (i.e. absolute received signal strength) and further uses static thresholds of signal strength for matching. Further, signal strengths from different orientations are averaged into one value for a location resulting in loss of detail, as signal strength can vary greatly with respect to orientation.

Method, system and apparatus for locating a mobile communications device


A parallel processing device includes a processing sequence management unit that reads commands of the command corresponding to a parallel processing start bit to the command corresponding to a parallel processing completion bit from a sequence command storage in sequence to make the sequence command storage output the commands to a first address management unit and a second address management unit, the first address management unit refers to the sequence commands read from the sequence command storage in order from the head to find the command that a first processing execution unit executes, and then instructs the first processing execution unit to execute the command, and the second address management unit refers to the sequence commands read from the sequence command storage in order from the head to find the command that a second processing execution unit executes, and then instructs the second processing execution unit to execute the command.

There has been known a data processor multiprocessing a data-driven program and a control-driven program on the same pipeline, on an instruction-by-instruction basis (see, for example, Patent Document 1).
Further, there has been known a processor obtaining a data transfer instruction in a cache memory as a combination of plural instructions (see, for example, Patent Document 2).
Further, there has been known a general-purpose processor that fetches each instruction from an instruction register or fetches plural instructions from an instruction register at the same time and is capable of performing dynamic pipeline control that executes decoded plural operation instructions (see, for example, Patent Document 3).
There has been known a parallel computer system that is configured by a plurality of computers and a communication mechanism communicating them, employs a configuration in which a single job is divided into plural processes to be assigned to the computers, broadcasts a piece or pieces of process progress information of the single or plural process/processes to operate in each of the computers itself to all the computers via the communication mechanism, and executes processes to be assigned while being in synchronization with a process to operate in another computer in accordance with the piece or pieces of process progress information broadcasted via the communication mechanism (see, for example, Patent Document 4).
[Patent Document 1] Japanese Laid-open Patent Publication No. 2005-108086
[Patent Document 2] Japanese Laid-open Patent Publication No. 2006-313422
[Patent Document 3] Japanese Laid-open Patent Publication No. 11-161491
[Patent Document 4] Japanese Laid-open Patent Publication No. 10-83379
There can be considered a parallel processing device that includes: a plurality of processing execution units parallel processing commands; and a management unit supplying each command to be executed to the plural processing execution units. However, when the management unit manages all the processing execution units, there is caused a problem that a circuit scale is increased.


An etch stop layer is formed over a first structure by depositing a metal oxide material over the first structure and annealing the deposited metal oxide material. A second structure is formed over the etch stop layer, and a formation is etched through the second structure using the etch stop layer as an etch stop.

1. Field of the Invention
The present invention generally relates to the field of semiconductor devices, and more particularly, the present invention relates to etch stop structures and methods utilized in the manufacture of semiconductor devices.
2. Description of the Related Art
The use of etch stop layers in the manufacture of semiconductor devices is well known in the art. In addition to signaling the termination point of an etching process used to remove an overlying layer or layers, the etch stop layer functions to protect any underlying layer or layers during the etching process. However, one drawback encountered with the conventional use of etch stop layers occurs when an edge of the etch stop layer abuts against a conductive layer during wet etching of a layer formed over the etch stop layer. In this case, the etchant used in the wet etch process can permeate between the etch stop layer and the conductive layer, thus causing damage to the layer or layers underlying the etch stop layer. An example of this problem is presented below in the context of the manufacture of a cylindrical memory cell capacitor.
FIGS. 1A through 1F are schematic cross-sectional views for explaining a method of manufacturing a memory cell in which the lower electrode of the capacitor thereof has a cylindrical structure. Referring initially to FIG. 1A, a plurality of impurity regions (not shown) are formed in the surface of a semiconductor substrate 5. An interlayer dielectric (ILD) 10 is then formed over the substrate 5, and contact pad holes 15 are selectively etched in the ILD 10 to expose the respective impurity regions. The contact holes 15 are then filled with respective contact pads 20. Then, a first etch stop layer 25, a support insulator layer 30, a second etch stop layer 35, a mold layer 40, and an anti-reflection film 45 are successively formed over the ILD 10 as shown. The first and second etch stop layers 25 and 35 are typically formed of silicon nitride (Si3N4).
Then, as illustrated in FIG. 1B, a photoresist film pattern 50 is formed over the anti-reflection film 45, and thereafter the anti-reflection film 45, the mold layer 40, the second etch stop layer 35, the support insulator layer 30, and the first etch stop layer 25 are all etched to define node holes 55 which expose the respective contact pads 20. Here, the etching process typically both dry etch and wet etch processes. In this case, referring to FIG. 1C, sidewall portions of the mold layer 40 and support insulator layer 30 may be eroded, resulting in the protrusion of the exposed edges of the first and second etch stop layers 25 and 35. Likewise, an upper surface portion of the ILD 10 may be removed by the wet etching, resulting in the protrusion of the upper end of the contact pad 20 from the surface of the ILD 10.
Referring still to FIG. 1C, a storage node 60 is conformably formed on sidewall and bottom walls of the node hole 55 (FIG. 1B). The storage node 60 is typically form of titanium nitride (TiN). Then, a sacrificial layer 65 is formed on the resultant structure to as to fill the node hole 55.
Then, as illustrated in FIG. 1D, the sacrificial layer 65 and the storage node 60 are planarized (typically by CMP) to expose the upper surface portion of the mold layer 40. In FIG. 1D, the planarized sacrificial layer is identified by reference number 75, and the planarized storage node is identified by reference number 70.
Referring next to FIG. 1E, a wet etch process is executed to remove the mold layer 40 (FIG. 1D) and the sacrificial layer 75 (FIG. 1D). The wet etchant used in this process must exhibit etch selectivity with respect to the storage node 70 and the silicon nitride etch stop layer 35. Unfortunately, however, in practice the silicon nitride etch stop layers 35 and 25 are easily eroded by the wet etchant used to remove the mold and sacrificial layers. As a result, referring to reference numbers A1 and A2 of FIG. 1E, the wet etchant tends to permeate between the storage node 70 and the etch stop layers 35 and 25, thus damaging the underlying insulating layer 30 and ILD 10, respectively.
Turing now to FIG. 1F, the memory cell is essentially completed by conformally depositing a dielectric layer 80 on the exposed surfaces of the storage node 70, and by then forming a plate node layer 85 on the resultant structure as shown. Note that the capacitive element 90 of the memory cell is constituted by the storage node 70, the dielectric layer 80, and the plate node layer 85.
As described above, the use of conventional etch stop layers may result in fabrication problems. For example, problems occur when an edge of a conventional etch stop layer abuts against a conductive layer during wet etching of a layer formed over the etch stop layer. In the case of fabricating a cylindrical capacitor electrode, the wet etchant may permeate between the etch stop layer and a storage node during removal of mold and sacrificial layers, thus causing damage to the layer or layers underlying the etch stop layer.

Etch stop structure and method of manufacture, and semiconductor device and method of manufacture


Systems and related methods are disclosed herein that generally involve focusing dispersed ions using one or more DC ion funnels. In some embodiments, a DC ion funnel is provided that includes a plurality of ring-shaped electrodes, each having an aperture formed therein such that the funnel defines an interior volume extending between an ion inlet and an ion outlet. A controller applies a DC potential to each of the electrodes without applying an RF potential to any of the electrodes, such that ions entering the funnel are substantially confined within said volume. The interior volume can have any of a variety of shapes, such as cylindrical, frusto-conical, and curved frusto-conical. In addition, any of a variety of DC potentials can be applied to the plurality of electrodes.

A typical mass spectrometer includes an ion source module, an analyzer module, and a detector module. Typically, in the ion source module, a sample that is to be analyzed is converted to an ion beam comprising a plurality of charged particles dispersed in a carrier gas. The analyzer module separates the charged particles according to their mass using electromagnetic fields. The detector module then measures or calculates the abundance of various types of ions to provide information for determining the composition of the sample.
Usually, the ion source module operates at or near atmospheric pressure (e.g., in the case of atmospheric-pressure ionization (API) and atmospheric-pressure chemical ionization (APCI) ion sources). The analyzer module, however, usually requires high vacuum conditions to operate effectively. To transport ions that are generated at atmospheric pressure and contained within a carrier gas into a vacuum region, an orifice plate typically is used that defines a sampling orifice through which the ions are able to pass. The sampling orifice is generally quite small (e.g., 1 mm in diameter) to enable maintenance of a high pressure differential across the orifice plate. In addition, the analyzer module can include several stages of differential pumping to create large pressure differences, in which case each of a plurality of pressure regions are connected in series through apertures in order to allow gas flow from one pressure region to the next. Due to the limited size of the sampling orifice and the apertures between each pressure region, a significant portion of the dispersed ions fail to pass through such openings. As a result, many ions of interest are lost, and the overall sensitivity of the system is reduced.
A number of systems have been proposed to focus an ion beam towards an opening so as to increase the proportion of ions that pass through the opening and thereby improve system sensitivity. For example, a radio frequency (RF) ion funnel has been proposed that includes a plurality of axially-aligned ring-shaped electrodes mounted in proximity to an opening through which the ion beam is to be directed. Each electrode has an inner diameter that is less than that of the immediately-preceding electrode, such that ions travelling in the axial direction towards the opening encounter electrodes having progressively-smaller inner diameters. RF potentials are applied to each of the electrodes, and the phase of the RF potential is varied from one electrode to the next. Ions travelling towards the periphery of the RF ion funnel are repelled by the field existing near the surface of the electrodes, and are thereby urged towards, and substantially confined to, the essentially field-free center region of the RF ion funnel. Meanwhile, much of the carrier gas is permitted to escape the RF ion funnel through spaces between adjacent electrodes.
While RF ion funnels have shown some promise, they suffer from a number of shortcomings. Most notably, the ability of such systems to effectively confine ions deteriorates rapidly as operating pressure increases. Thus, if the sampling orifice or apertures between pressure regions are increased in size to allow more ions to pass, the operating pressure quickly reaches a point at which the RF ion funnel becomes ineffective. In addition, RF ion funnels require a large amount of RF power to operate, especially when higher RF frequencies are used to allow the system to operate at higher pressures.
Accordingly, a need exists for improved systems and methods for focusing dispersed ions.
Further introductory information can be found in the following references, the entire content of each of which is incorporated herein by reference:
U.S. Pat. No. 6,107,628 to Smith et al., entitled "METHOD AND APPARATUS FOR DIRECTING IONS AND OTHER CHARGED PARTICLES GENERATED AT NEAR ATMOSPHERIC PRESSURES INTO A REGION UNDER VACUUM";
U.S. Pat. No. 6,639,213 to Gillig et al., entitled "PERIODIC FIELD FOCUSING ION MOBILITY SPECTROMETER";
U.S. Pat. No. 7,223,969 to Schultz et al., entitled "ION MOBILITY TOF/MALDI/MS USING DRIFT CELL ALTERNATING HIGH AND LOW ELECTRICAL FIELD REGIONS";
U.S. Pat. No. 7,259,371 to Collings et al., entitled "METHOD AND APPARATUS FOR IMPROVED SENSITIVITY IN A MASS SPECTROMETER";
U.S. Pat. No. 7,365,319 to Hager et al., entitled "METHOD FOR PROVIDING BARRIER FIELDS AT THE ENTRANCE AND EXIT END OF A MASS SPECTROMETER";
U.S. Patent Publication No. 2010/0038532 to Makarov et al., entitled "EFFICIENT ATMOSPHERIC PRESSURE INTERFACE FOR MASS SPECTROMETERS AND METHOD";
GERLICH, "Inhomogeneous RF Fields: A Versatile Tool for the Study of Processes with Slow Ions," Advances in Chemical Physics Series, Vol. LXXXII (1992);
GUAN et al., "Stacked-Ring Electrostatic Ion Guide," Journal of American Society for Mass Spectrometry 1996, 7, 101-106; and
KREMER et al., "A Novel Method for the Collimation of Ions at Atmospheric Pressure," Journal of Physics D: Applied Physics 39 (2006) 5008-5015.