High-level Components Research Articles

Low energy x-ray response of Ge detectors with amorphous Ge entrance contacts

The low energy X-ray response of Ge detectors with amorphous Ge entrance contacts has been evaluated. The spectral background due to near contact incomplete charge collection was found to consist of two components: a low level component which is insensitive to applied voltage and a high level step-like component which is voltage dependent. At high operating voltages, the high level component can be completely suppressed, resulting in background levels which are much lower than those previously observed using Ge detectors with Pd surface barrier or B ion implanted contacts, and which also compare favorably to those obtained with Si(Li) X-ray detectors. The response of these detectors to /sup 55/Fe and 1.77 keV X-rays is shown. A qualitative explanation of the origins of the observed background components is presented. >

Architecture of the Encina distributed transaction processing family

This paper discusses how the Encina® family of distributed transaction processing software can be used to build reliable, distributed applications. We start with the toolkit components of Encina and how they are used for implementing ACID properties. We then consider how the toolkit can be applied in building higher level components in a DCE environment. We conclude with a discussion of the Encina Monitor, which provides a framework for organizing a collection of machines and servers.

LEARNING BLACKBOARD-BASED SCHEDULING ALGORITHMS FOR COMPUTER VISION

The goal of image understanding by computer is to identify objects in visual images and (if necessary) to determine their location and orientation. Objects are identified by comparing data extracted from images to an a priori description of the object or object class in memory. It is a generally accepted premise that, in many domains, the timely and appropriate use of knowledge can substantially reduce the complexity of matching image data to object descriptions. Because of the variety and scope of knowledge relevant to different object classes, contexts and viewing conditions, blackboard architectures are well suited to the task of selecting and applying the relevant knowledge to each situation as it is encountered. This paper reviews ten years of work on the UMass VISIONS system and its blackboard-based high-level component, the schema system. The schema system could interpret complex natural scenes when given carefully crafted knowledge bases describing the domain, but its application in practice was limited by the problem of model (knowledge base) acquisition. Experience with the schema system convinced us that learning techniques must be embedded in vision systems of the future to reduce or eliminate the knowledge engineering aspects of system construction. The Schema Learning System (SLS) is a supervised learning system for acquiring knowledge-directed object recognition (control) strategies from training images. The recognition strategies are precompiled reactive sequences of knowledge source invocations that replace the dynamic scheduler found in most blackboard systems. Each strategy is specialized to recognize instances of a specific object class within a specific context. Since the strategies are learned automatically, the knowledge base contains only general-purpose knowledge sources rather than problem-specific control heuristics or sequencing information.

Structural Analysis of Models with Composite Dependent Variables

Composite variables are those that may be mathematically decomposed into additive and/or multiplicative component variables. Several researchers have noted that the relationship between a composite variable and its components may be a mathematical artifact, but the effect of their inclusion as independent variables on the coefficients of the remaining variables in the model has not been recognized, nor has a formal expression for the resulting bias been presented. Structural analysis of composite dependent variables, as presented here, provides the key to understanding the nature and extent of this bias. It separates higher and lower level components from one another and also separates these components from other antecedent variables in the model. The advantages of this hierarchical decomposition are that (1) it reduces problems of misspecification and omitted variables, (2) by separately estimating antecedent effects on each component, it offers some insights into the underlying causal mechanisms that are not available from other techniques and (3) it ensures that regression coefficients can be interpreted in the standard way: the expected change in the dependent variable associated with a change in the independent variable, holding other independent variables in the equation constant. Moreover, hierarchical decomposition of the dependent variable can reproduce all information available from techniques that mix levels of analysis, but the converse is not true.

Changes in Overhand Throwing Patterns as a Function of Ball Size

Ten males and 10 females in each of four grade/age groups threw styrofoam balls of six different diameters as hard as possible at a wall 6.7 m away. Each ball size was thrown four times. The first hypothesis, that the levels of the five components of the one-hand overhand throw would be quite stable for individuals for throws of a particular ball size, was supported. Ball sizes at which the component levels were unstable marked the beginning of a transition to a new component level 70.6% of the time. The second hypothesis, that five components would change from higher to lower levels for most of the subjects as ball size was scaled up, was supported only for the backswing and forearm components. These components were more likely to be affected by increasing ball size because the higher level components required a firm, one-hand grip on the ball, which became more difficult as ball diameters exceeded the subjects’ hand widths. The results indicate that practitioners need to recognize that different ball sizes may elicit different throwing patterns, and specifically that a critical ball diameter may be reached when it is equal to hand width.

Visual Illusory Productions with or without Amodal Completion

A new type of illusory contour is presented whose appearance is generated by the graphic representation of groups of human figures interacting in a coordinated manner with external reality. When numerous pictorial indicators of cause-effect relationships are provided, and appropriate techniques and sufficiently ambiguous observation conditions are used, hallucinatory objects congruent with expectations linked to the meaning of the configurations appear. There is thus a high-level semantic component that is active in the formation of visual illusory contours and is even capable of interacting with other known factors: brightness contrast, the number of elements, the degree of alignment of the elements, etc. This new type of illusory contour fits current definitions and can be experimentally modified. The variations in subjective clarity scores are presented for a study in which twenty subjects observed nineteen experimental figures, certain variables of which were manipulated. The issue is worthy of further experimental investigation.

Computation structures

From the Publisher: Computation Structures integrates thorough coverage of digital logic design with a comprehensive presentation of computer architecture. It contains a wealth of information for anyone who designs computers or works with computer systems. Indeed, the authors' goal is to teach people to look at systems, as a whole, without being bound by the artificial interfaces that are often used to train specialist engineers. Ward and Halstead demystify the construction of computing hardware by illustrating how it is built up from digital circuits through higher-level components to processors and memories and emphasizing how the design of hardware is affected by its intended use. The book is firmly based in the real world, with pertinent discussions of the many trade-off decisions practicing engineers must confront. Throughout the book, the authors use the running example of the MAYBE computer--a simple microarchitecture that readers can construct and operate--to establish connections between theory and real-world practice. Among the topics addressed are the digital abstracts; combinatorial devices and circuits; the synthesis of digital systems; finite-state machines; control structures and disciplines; performance measures and trade-offs; communication; interpretation; microinterpreter architectures; microprogramming; single-sequence machines; stack, register, and memory architectures; RISC machines; processes; interrupts and priorities; and architectural horizons.

Disturbance caused by various fluctuating single noises and combined community noises

Three experiments were conducted to investigate factors influencing the (rated) disturbance caused by various noises to subjects when they were reading: (a) comparison of disturbances from various noises at 70 dB(A) L eq; (b) comparison of exposure-response relationships between road traffic, aircraft, and train noises; and (c) the effect of road traffic background noise on the total disturbance caused by combined noise (aircraft or train noise combined with road traffic noise). From the three experiments, the following conclusions were drawn: (1) High-level components such as peak level contributed to the disturbance, since the noise was more disturbing with the increase of peak level. (2) Although the general pattern of the exposure-response relationships for aircraft and train noises was similar, the disturbance due to road traffic noise increased with L eq level more rapidly than for aircraft and train noise. Considering that the peak level of aircraft or train noise was always higher than that of road traffic noise at equal L eq levels, the contribution of the high-level components to the disturbance appeared to be level-dependent. (3) The background noise level did not affect the total disturbance. Because the high-level components of combined noises were almost the same, this finding was consistent with conclusions drawn in (1) and (2).

PARLE: A language for expressing parallelism and integrating symbolic and numeric computations

The Parallel Architectures Research Language PARLE, described here, is the higher-level component of the SPAN Kernel System, in which it acts as a compilation target. Support for integrated symbolic and numeric processing is provided through the facility to treat lists and arrays as synonymous data-structures known as n-ary lists; by permitting the use of asynchronous processes; and by allowing a high degree of dynamicity in the creation of local processes. In addition, PARLE is a procedural programming language, and hence shares the control-flow attributes of present time numeric languages. Support for parallelism is provided through simple control mechanisms to specify parallelism both at the statement level and at the processor level. This is achieved by a capability to explicitly define processors and treat such processor definitions as a means of grouping code and data definitions. To enable inter-processor communication, all processors are treated as residing within a shared address space and communicate using primitives for message-passing.

Multiprocessor software for the CYBERPLUS high performance system

This paper describes the results of the research for implementing applications for concurrent execution on the CYBERPLUS multiparallel computer system. Three layers of parallelism are built into this system: instruction, computation and functional levels. The paper contains a short summary of the hardware, and the different layers of the software for multiprocessor systems. They are based on the previously developed CPFTN (Cyberplus Fortran Compiler) compiler which produces optimized object code for a single CYBERPLUS processor, exploiting through a series of horizontal and vertical optimizations the internal parallelism present in this processor. Unlike other compilers, the input to CPFTN consists of an entire kernel containing all subroutines and functions loaded into a single processor. An interprocessor communications subsystem provides the low-level component of the multiprocessor system and contains the data transfer and synchronization capabilities. The high-level component consists of extensions to FORTRAN (CPMFTN, Cyberplus Multiprocessor Fortran) for characterizing the data shared between processors and implements concepts specially adapted to the private memory architecture of the CYBERPLUS as well as to the specific needs of the user community targetted by this product. The resulting scheme is a large grain size, demand driven, data flow type. It is assumed that partition between processors can best be done on the bases of the high-level knowledge of the problem possessed by the user. The corresponding kernels may be created independently of each other, using the new language features introduced to characterize data shared between processors. Scheduling, synchronization, as well as data transfer operations are automatically distributed by the compiler across the subroutines and functions constituting the grain size of the partition. The first version of CPMFTN under development is described followed by several simple application paradigms and discussion of the merits of possible future extensions.

A generic operations system interface to support the next generation of digital loop carrier systems

The application of a generic interface between operations systems and microprocessor controlled network elements (OS/NE) to both universal and integrated DLC (digital loop carrier) systems is discussed. The high-level components of a DLC system are defined, and a generic interface between operations systems and their central office terminal of a microprocessor-controlled DLC system is described. The adaptation of the generic operations-systems interface to the DLC system for use with a generic interface between the local switching system and the remote digital terminal of an integrated DLC system is explored. Some issues associated with integrating a DLC system into a switching system are presented. >

Absorption spectrum of atomic chlorine 950 Å to 600 Å

The experimental study of atomic chlorine absorption spectra by using a flash-pyrolysis system and a 2-m normal incidence spectrograph in the wavelength region 950 Å to 600 Å has produced wavelength measurements, line series identifications involving the 1D and 1S limits, and photoabsorption cross sections. The absorption spectra involve transitions from both levels (2P03/2 and 2P01/2) of the ground state doublet.About 178 lines are identified and assigned to 16 series and have led to the classification of 116 even levels.Our relative photoabsorption cross section measurements which cover the 950 Å to 600 Å range have been normalized to the photoionization continuum cross sections of Samson, Shefer and Angel [9] within the wavelength range 755-600 Å. Our results and Ruščić and Berkowitz [8] compare well on this same absolute scale between 760 Å and 960 Å for the broad autoionizing features. The expected additional features, which originated from transitions involving the higher level component of ground state doublet are seen.

Dynamic multi-level simulation of digital hardware designs

This paper presents the issue of dynamic multi-level simulation of hardware designs that addresses the problem of inefficiency associated with the conventional static multi-level simulation ap proaches as in ADLIB-SABLE (Hill 1980), DIANA (Demou and Arnout 1979), and SPLICE (Newton 1978). In this approach, digital sim ulation or verification (McWilliams 1980) of hardware designs is initiated at a high level of abstraction. When detailed results are required for one or more high-level components or for tracing the source of an error to any of the lower-level devices, the appropriate components are expanded into their lower-level implementations. Then simulation or verification initiates at that level. Following completion of execution at the lower level, con trol returns to the higher level. Consequently, only those sub parts of a digital design are selected for expansion and detailed simulation that are dynamically warranted by the higher-level simulation results. Unnecessary simulation effort may be elimi nated. Dynamic multi-level simulation or zooming is a generaliza tion of the swapping technique (Szygenda 1973) to functional and fault simulation and timing verification and to the differ ent abstraction levels in the hierarchy between the gate- and behavior-levels. This paper also addresses the implementation of zooming in the rule-based design verifier, RDV (Ghosh 1984), at Stanford University. That RDV uses Ada (U.S. Dept. of Defense 1983) as a hardware description language and simulation envi ronment (Ghosh 1985).

The interchangeability of safety stocks and safety lead time

AbstractDue to the uncertainty in estimating both the demand for end products and the supply of components from lower levels, buffering techniques should be included before the loading of a material requirement planning (MRP) system. Safety stocks and safety lead time are two techniques of providing buffering for loading. There have been many studies made concerning the determination of the amount of safety stocks and safety lead time. Some guidelines for choosing between safety stocks and safety lead time for dealing with uncertainty in both demand and supply also have been established. Although these two different methods have been used successfully, it has not been documented that using these two methods in a given situation will yield essentially the same results; that is, the interchangeability of these two buffering techniques has not been explored quantitatively.Since the net influence of safety stocks and safety lead time and their quantitative interchangeability are of major interest, an analytical model is proposed for this study. The lead‐time offset procedure for components loading are represented by a matrix model that is based on a lot‐for‐lot lot‐sizing technique. This lead‐time offset matrix model is the product of the precedence matrix and the fixed‐duration matrix. The precedence matrix is formed according to the total requirement factor matrix and the duration matrix is formed by each component process time. Thus, the lead‐time offset matrix will generate the starting period of each component.When the lead‐time offset procedure is modeled, the net influence of buffering quantity can be analyzed. The planned safety stock that is normally used to accommodate unexpected demand, shortage in supply, and defects from the operation at each process can be combined with demand to form the master production schedule. The revised lead time due to the integration of the safety stocks can be calculated through the lead‐time offset model. The safety lead time may extend the component process time as well as overall production lead time if the designated safety lead time is longer than the available slack time in a fixed lead‐time loading system.When the proposed lead‐time offset model is further examined, it is found that planned safety stocks at the higher level can buffer the fluctuations of lower level components quantity as well as the fluctuations of same level components quantity. Safety stocks can also buffer shortages that are caused by the delay of raw material and manufacturing processes. Thus, safety stocks can be used to buffer unexpected delay time up to certain limits. A planned safety lead time at higher level component process can buffer the fluctuations of lower level components process time, as well as the same level component process time. The safety lead time can be used to produce additional products to meet unexpected excessive demand up to certain limits under the following conditions: 1. The excessive demand is known before the actual processing of the components in the lowest level. 2. The raw material at the lowest level is available.Although safety stocks and safety lead time are interchangeable in terms of the ability to buffer variations in quantity, the conditions for safety lead time are seldom met in actual practices. Thus, the slack time in a fixed lead‐time loading system cannot be considered as an effective measure to substitute safety stocks. However, all or part of the delay in manufacturing processes or the supply from the lower level components can be buffered by the safety stock and the MPS will still be met. From this study, it is obvious that the slack time can be reduced when safety stocks are planned for an MRP system. The reduction of fixed lead‐time duration will be beneficial to the overall planning and scheduling in MRP systems.

Fatigability of the stapedius reflex in industrial noise. A field study.

The depression of the stapedius reflex after a whole workday in industrial noise was studied in 11 normal-hearing employees at a shipbuilding yard. The reflex activity was assessed with simultaneous bilateral recordings of impedance change induced by stimulation with 2 000 and 500 Hz tones. One ear was exposed for approximately 7 hours in the plant, the other one was protected. The dose was measured individually at 89--103 dB(A) equivalent level. Utilization of bilateral recordings together with a unilateral exposure enabled an analysis based on the whole stimulus response curves. The results show that the reflex is depressed on the average 4 dB at 2 000 Hz 10 min after end of workday. By extrapolation the stapedius reflex was estimated to be depressed less than 10 dB at the end of the exposure. Since the stimulus-response curves are shifted in parallel, the contraction during the high-level components of the noise were largely unaffected. No evidence was found for creation of transtympanic pressure differences during noise exposure. It was concluded that the reflex fulfils one necessary condition for influencing the individual pattern of noise damage to the ear, fatigue resistance in the presence of long-term exposure to hazardous noise.

The seasonal changes in body weight and biochemical composition of the warm-temperate cirripede Chthamalus stellatus (Poli)

Seasonal changes in the body weight and biochemical composition have been determined for the warm-temperature cirripede, Chthamalus stellatus (Poli). In the absence of a more easily measured yet reliable parameter a standard animal has been related to the amount of chitin present. There are considerable differences in the seasonal changes in the body weight for the several years over which the observations were made. These differences were not correlated with the spring increase of diatoms as measured by the chlorophyll content of water samples. C. stellatus in this area lives high up the shore: the variations are correlated with the deviations from the mean period of water cover: the time of coverage by water is often much different at such high levels from that calculated from tide tables. This factor is probably important when considering similar changes in other animals restricted to high levels or even to the high level components of less restricted populations. The amounts of carbohydrate, lipid, and nitrogen, both soluble and insoluble (‘protein’) do not vary in a systematic manner with season over the three-year period investigated.

Notice of Bogardus' universal eccentric mill for hulling, cutting, and grinding

Vibration displacements and accelerations have been monitored on a modified Amsler machine during the dry rolling-sliding wear testing of rail steels. Certain combinations of contact stress and creepage lead to periodic circumferential surface deformations of the test discs, termed corrugations. The low frequency corrugations are defined as facets. Dramatic facets have occurred at 500 MPa maximum Hertzian contact stress and 10% creepage, in the frequency band ranging from 1–100 Hz, with a typical facet frequency initiated at 58.25 Hz. No higher frequency corrugations occurred during the test run, unlike previous tests (J.E. Garnham, J.R. Brightling and J.H. Beynon, Wear, 124 (1988) 45–63).The evolution of the surface deformation was observed by surface profilometry, as well as by monitoring the facet vibration component trend, and a good correlation between the two has been found. Also, a significant correlation between the predominant peaks of the displacement spectra and the higher harmonics of the rotation frequency have been detected, leading to conclusions concerning the mechanism of facet initiation. At the end of the test the facets degenerated into pronounced eccentricities causing a high level component of the rotation frequency that could easily be detected by following the evolution of the characteristic component. The tests highlighted that the vibration displacement is more suitable for the monitoring of rolling-sliding contact defects than is the acceleration, which tends to emphasise the high frequency components. Vibration monitoring is shown to be a proper and powerful tool for the early detection of facet initiation.