Effect of Shot Peening Operation on the Microstructure and Wear Behavior of AZ31 Magnesium Alloy

Protection of Metals and Physical Chemistry of Surfaces - Shot peening is a treatment used to increase surface hardness and wear resistance. In this study, the effect of shot peening on the...     

The syndrome of thrombosis, thrombocytopenia, and recurrent spontaneous abortions associated with antiphospholipid antibodies: Hughes syndrome

aPL-associated thrombosis (Hughes syndrome) is widely recognized as a major cause of organ damage in autoimmune diseases. Beginning with the first symposium in 1984, international aPL symposia have facilitated research on aPL antibodies, and the clinical standardization of aPL tests. It is hoped that the present symposium will continue this tradition, because much remains to be learnt about the origin and pathogenicity of aPL antibodies. In addition, new insights are needed for more effective therapies to be developed.     

Video Transmission for Third Generation Wireless Communication Systems

This paper presents a twin-class unequal protected video transmission system over wireless channels. Video partitioning based on a separation of the Variable Length Coded (VLC) Discrete Cosine Transform (DCT) coefficients within each block is considered for constant bitrate transmission (CBR). In the splitting process the fraction of bits assigned to each of the two partitions is adjusted according to the requirements of the unequal error protection scheme employed. Subsequently, partitioning is applied to the ITU-T H.263 coding standard. As a transport vehicle, we have considered one of the leading third generation cellular radio standards known as WCDMA. A dual-priority transmission system is then invoked on the WCDMA system where the video data, after being broken into two streams, is unequally protected. We use a very simple error correction coding scheme for illustration and then propose more sophisticated forms of unequal protection of the digitized video signals. We show that this strategy results in a significantly higher quality of the reconstructed video data when it is transmitted over time-varying multipath fading channels.     

Combination of mechanical and informational modeling to predict hysteresis behavior of I beam‐to‐CFT column connection

The behavior of beam‐to‐column connections is significantly complicated because it depends on the material, nonlinear relationship between different members, and contact of connecting elements. Their hysteretic response exhibits highly inelastic characteristics and continuous variation in stiffness, strength, and ductility. Therefore, accurate hysteretic models of bolted connections are essential to accurate seismic assessment and design. Composed (Hybrid) modeling approach is presented to represent the complex hysteretic behavior of I beam‐to‐concrete‐filled‐tube (CFT) column bolted connection. For the purpose in this study, experimental evaluation of I beam‐to‐CFT column connection with bolted end‐plate under cyclic loading is done. It must be mentioned to make the connection easily applicable practically and also prepare the column flanges continuity, a connection with the bolts penetrated into the CFT column are used since using the stiffeners in hollow sections is not easily applicable. In the composed mechanical–informational modeling framework, the conventional mechanical model is complemented by information‐based model components. Finally, moment–rotation curves of composed model have been compared with experimental results. Comparison showed that the composed model has a good agreement with experimental results. A newly designed specimen for validation purpose of the composed modeling was made and experimented. Composed model was well applied to predict the behavior of new connections. The presented results show that the composed model has a good ability to predict of hysteretic behavior.     

Evaluation of the moment-rotation curve of I beam-to-CFT column connection with endplate,using mechanical modeling

Through this study, a method is presented to estimate moment-rotation (M-) curve of I beam-to-the concrete filled tube (CFT) connections. This method is based on the components method in which components are analyzed and modeled as different mechanical models. These components are considered as springs with specific mechanical properties of stiffness, strength, and rigid bars. Their force-displacement relationship is assumed bi-linear and 3-linear. The connection behavior is assumed through assembling the stiffness of different components. In this study, connection of I beam-to-CFT column with bolted endplate connection under monotonic loading, which has been tested in the laboratory, is evaluated. It must be mentioned that those bolts which penetrated into the column depth have been used in order to create continuity between flanges of the column. The suggested method has been compared with the experimental test and the advanced finite element model in terms of stiffness, strength, and rotational capacity; moreover, its operation was satisfactory.     

Rate adaptive video transmission over ad-hoc networks

A packet control mechanism via a cross-layer feedback to reduce bursts of packet drops for transmission of video over mobile multihop ad-hoc networks is presented. With this approach, the application layer would be capable of controlling the packet transmission flow in accordance with the multihop characteristics of the routing layer.     

Multihop sensor network design for wide-band communications

This paper presents a master/slave cellular-based mobile ad hoc network architecture for multihop multimedia communications. The proposed network is based on a new paradigm for solving the problem of cluster-based ad hoc routing when utilizing existing wireless local area network (WLAN) technologies. The network architecture is a mixture of two different types of networks: infrastructure (master-and-slave) and ad hoc. In this architecture, the participating slave nodes (SNs) in each cluster communicate with each other via their respective master nodes (MNs) in an infrastructure network. In contrast to traditional cellular networks where the base stations are fixed (e.g., interconnected via a wired backbone), in this network the MNs (e.g., base stations) are mobile; thus, interconnection is accomplished dynamically and in an ad hoc manner. For network implementation, the IEEE 802.11 WLAN has been deployed. Since there is no stationary node in this network, all the nodes in a cluster may have to move together as a group. However, in order to allow a mobile node to move to another cluster, which requires changing its point of attachment, a handoff process utilizing Mobile IP version 6 (IPv6) has been considered. For ad hoc routing between the master nodes (i.e., MNs), the Ad hoc On-demand Distance Vector (AODV) Routing protocol has been deployed. In assessing the network performance, field test trials have been carried out to measure the proposed network performance. These measurements include packet loss, delays under various test conditions such as a change of ad hoc route, handoffs, etc.     

Do patients with antiphospholipid syndrome have autoantibodies to beta 2-glycoprotein I?

High positive anticardiolipin antibody tests have been associated with recurrent thrombosis and pregnancy loss. Although these antibodies were believed to bind negatively charged phospholipids, recent reports have suggested that a serum protein, beta 2-glycoprotein I (beta 2-GPI), may be the true antigen for these antibodies. To resolve this issue, we compared binding of 75 anticardiolipin-positive and 71 anticardiolipin-negative serum samples from patients with rheumatic diseases to beta 2-GPI by using an enzyme-linked immunosorbent assay (ELISA). Serum samples from 30 healthy blood donors and 10 laboratory personnel were used as normal controls. We found no difference in binding between the three groups of serum samples. In addition, when binding to beta 2-GPI coated plates was compared with binding to ELISA plates without beta 2-GPI (blank), no difference was observed. Finally, binding of anticardiolipin-positive serum samples to plates coated with cardiolipin-beta 2-GPI mixture varied directly with the cardiolipin concentrations. Based on these findings, we conclude that anticardiolipin-positive serum samples do not bind beta 2-GPI.     

Block adaptive prediction of colour television signals

A single coefficient block-adaptive predictor is described for encoding of colour television signals. The optimum coefficients were obtained for each block of incoming samples according to the selection of sampling frequency. The results show a reduction in large prediction errors, compared with a nonadaptive predictor, and also improvements in signal/prediction-noise ratio.     

Noninteger sampling to subcarrier frequency ratios in d.p.c.m. of PAL signals

A simple predictor having three coefficients is described for d.p.c.m. encoding of composite PAL colour signals. Noninteger ratios of sampling frequency fs to subcarrier frequency fsc can be selected. For a colour-bar signal, it is shown that the s.n.r. of the d.p.c.m. system using fs/fsc = 2.5 is approximately the same as when third-previous sample prediction is used, i.e. when fs/fsc = 3.0.