Design and evaluation of an efficient traffic control scheme for integrated voice,video, and data over asynchronous transfer mode networks: Explicit allowed rate algorithm

Asychronous transfer mode (ATM) networks are high‐speed networks with guaranteed quality of service. The main cause of congestion in ATM networks is over utilization of physical bandwidth. Unlike constant bit‐rate (CBR) traffic, the bandwidth reserved by variable bit‐rate (VBR) traffic is not fully utilized at all instances. Hence, this unused bandwidth is allocated to available bit‐rate (ABR) traffic. As the bandwidth used by VBR traffic changes, available bandwidth for ABR traffic varies; i.e., available bandwidth for ABR traffic is inversely proportional to the bandwidth used by the VBR traffic. Based on this fact, a rate‐based congestion control algorithm, Explicit Allowed Rate Algorithm (EARA), is presented in this paper. EARA is compared with Proportional Rate Control Algorithm (PRCA) and Explicit Rate Indication Congestion Avoidance Algorithm (ERICA), in both LAN and WAN environments. Simulations of all three algorithms are conducted under both congestion and fairness configurations with simultaneous generation of CBR, rt‐VBR, nrt‐VBR and ABR traffic. The results show that, with very small over‐head on the switch, EARA significantly decreases the required buffer space and improves the network throughput. Copyright © 1999 John Wiley & Sons, Ltd.     

Re-Examining the Impact of Multidimensional Trust on Patients’ Online Medical Consultation Service Continuance Decision

Information Systems Frontiers - Recent years have witnessed the rapid growth of an emerging digital healthcare service – online medical consultation (OMC). Despite its popularity, many OMC...     

A service-oriented analysis of online product classification methods

Studies of Internet market have found that consumers' purchasing behaviors including information search, channel selection, and brand evaluation processes are impacted by the product/service types. In this research, we perform a comprehensive review of existing online product classification methods. An in-depth analysis of the rationale behind each method was studied, and important product characteristics were determined for integrating different approaches. Grounded on the theory of the components of perceived risk in product purchase and the recently emerged service science, the integrated classification will help companies to better understand the online consumer purchasing behavior and to design their e-commerce strategies accordingly. Survey results indicate that the integrated classification is an effective way to classify products and services marketed on the Internet.     

鞋履奇才Michel Perry的梦想庄园

Voudenay庄园位于著名的葡萄酒故乡——法国勃艮第(Bourgogne),建造于十八世纪,周围风景如画,一派诗情画意。这座美丽的庄园曾经破败不堪,仿如废墟,但被鞋履设计师Michel Perry购买、翻修后又重现生机。Michel Perry夫妇是在无意间发现Vaudenay庄园的,故事开始说     

Residual compression in area array packages induced by underfill shrinkage

A non-linear finite element model is developed to investigate underfill shrinkage as a possible source for obtaining beneficial residual compression in solder grid array interconnects. The axisymmetrical model geometry consists of a unit cell of concentric cylinders, the inner with properties representative of solder and the outer with properties representative of underfill, having an outer radius of half the array pitch. The solder, which is assumed to be eutectic, is modeled as an elastic–plastic material that exhibits creep behavior. The elastic modulus and Poisson’s ratio of the underfill material, E_u and ν_u, as well as the percentage of unconstrained linear shrinkage, , are varied to determine the influence these parameters have on the final steady-state stresses in the solder connections. To represent the underfill materials in common use, E_u ranged from 0.5 to 8.0 GPa, ν_u ranged from 0.2 to 0.4, and ranged from 0.2% to 1.0%. Upon shrinkage of the underfill during curing, the model predicts that the interconnect initially experiences residual compression in the axial direction. Due to tension in the radial direction, however, creep strain causes the axial compressive stress to lessen until a state of hydrostatic stress is reached. For the underfill properties tested, all the residual, steady-state stresses were compressive. The magnitude of this compression is shown in graphical form as a function of E_u, ν_u, and . An analytical expression for estimating the magnitude of residual compression as a function of these underfill properties is also included. The potential effect of the residual compression on the fatigue life of a package is discussed in the context of a particular example.     

On nonlinear controllability of homogeneous systems linear in control

This paper considers small-time local controllability (STLC) of single- and multiple-input systems, x/spl dot/=f/sub 0/(x)+/spl Sigma//sub i=1//sup m/f/sub i/u/sub i/ where f/sub 0/(x) contains homogeneous polynomials and f/sub 1/,...,f/sub m/ are constant vector fields. For single-input systems, it is shown that even-degree homogeneity precludes STLC if the state dimension is larger than one. This, along with the obvious result that for odd-degree homogeneous systems STLC is equivalent to accessibility, provides a complete characterization of STLC for this class of systems. In the multiple-input case, transformations on the input space are applied to homogeneous systems of degree two, an example of this type of system being motion of a rigid-body in a plane. Such input transformations are related via consideration of a tensor on the tangent space to congruence transformation of a matrix to one with zeros on the diagonal. Conditions are given for successful neutralization of bad type (1,2) brackets via congruence transformations.     

Epistemic motives and cultural conformity: Need for closure, culture, and context as determinants of conflict judgments.

Three studies support the proposal that need for closure (NFC) involves a desire for consensual validation that leads to cultural conformity. Individual differences in NFC interact with cultural group variables to determine East Asian versus Western differences in conflict style and procedural preferences (Study 1), information gathering in disputes (Study 2), and fairness judgment in reward allocations (Study 3). Results from experimental tests indicate that the relevance of NFC to cultural conformity reflects consensus motives rather than effort minimization (Study 2) or political conservatism (Study 3). Implications for research on conflict resolution and motivated cultural cognition are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Experimental study and life prediction on high cycle vibration fatigue in BGA packages

A technique and loading apparatus have been developed which allow ball grid array (BGA) packages to be visually inspected during high cycle vibration testing. This system provides controls for varying the cycling frequency and magnitude of the applied load. The failures of solder interconnects in BGA specimens were recorded by a direct visual monitoring method. Stroboscopic video was employed to freeze the motion of the vibrating solder interconnects while showing the real-time evolution of failure. In all test cases, BGA interconnect failure was observed to be the result of crack initiation and propagation along the nickel/solder interface. A primary crack developed at one edge of the interconnect and progressed stably until a secondary crack initiated from the opposite edge. The crack growth accelerated until these cracks coalesced, resulting in complete separation of the interconnect. The percentages of time spent in crack initiation, stable propagation and accelerated propagation are, on the order of 15%, 60% and 25%, respectively. Vibration tests at frequencies ranging from 50 to 100 Hz were performed and the number of cycles to failure was found to be frequency-independent in this range.Several commonly used damage mechanics and fracture mechanics fatigue life-prediction models are examined based on failure parameters computed from a nonlinear finite element analysis. It was found that while the damage models examined show large discrepancies between predicted and actual cycles-to-failure, the fracture model correlates with the test data within a factor of 1.5.