Behaviour of flush end plate joints to concrete-filled steel tubular columns

This paper presents the results of an experimental program for bolted moment connection joints of circular or square concrete filled steel tubular (CFST) columns, and H-shaped steel beams using high-strength blind bolts. In order to investigate the static performance and failure modes of the blind bolted connection, an experimental program was conducted involving four sub-assemblages of cruciform beam-to-column joints subjected to monotonic loading. Moment-rotation relationships of the tested connections were obtained and their performance was evaluated in terms of their stiffness, moment capacities and ductility. The test parameters varied were the column section type and the thickness of the end plate. The results showed that the proposed blind bolted connection, which behaves in a semi-rigid and partial strength manner according to the EC3 specification, displays reasonable strength and stiffness. The rotation capacity of this type of connection to square or circular CFST columns exceeds 70 mrad and this satisfies the ductility requirements for earthquake-resistance in most aseismic regions. The blind bolted connection is shown to be a reliable and effective solution for moment-resisting composite frame structures.     

Absorbed dose measurements of a handheld 50 kVP X-ray source in water with thermoluminescence dosemeters

Absorbed dose rate measurements of a 50 kV(p) handheld X-ray probe source in a water phantom are described. The X-ray generator is capable of currents of up to 40 microA, and is designed for cranial brachytherapy and intraoperative applications with applicators. The measurements were performed in a computer-controlled water phantom in which both the source and the detectors are mounted. Two different LiF thermoluminescence dosemeter (TLD) phosphors were employed for the measurements, MTS-N (LiF:Mg,Ti) and MCP-N (LiF:Mg,Cu,P). Two small ionisation chambers (0.02 and 0.0053 cm(3)) were also employed. The TLDs and chambers were positioned in watertight mounts made of water-equivalent plastic. The chambers were calibrated in terms of air-kerma rate, and conventional protocols were used to convert the measurements to absorbed dose rate. The TLDs were calibrated at National Institute of Standards and Technology (NIST) in terms of absorbed dose rate using a (60)Co teletherapy beam and narrow-spectrum X-ray beams. For the latter, absorbed dose was inferred from air-kerma rate using calculated air-kerma-to-dose conversion factors. The reference points of the various detectors were taken as the center of the TLD volumes and the entrance windows of the ionisation chambers. Measurements were made at distances of 3-45 mm from the detector reference point to the source center. In addition, energy dependence of response measurements of the TLDs used was made using NIST reference narrow spectrum X-ray beams. Measurement results showed reasonable agreement in absorbed dose rate determined from the energy dependence corrected TLD readings and from the ionisation chambers. Volume averaging effects of the TLDs at very close distances to the source were also evident.     

用于照明设备的高亮度LED驱动

随着高亮度(HB)LED效率的不断提高,即流明/瓦特(Lm/W)比的增加,越来越多的照明应用开始选择高亮度LED,例如汽车的外灯(日间行车灯,近光灯、远光灯)和普通照明设备等。LED生产厂家最近推出的高亮度LED的效率已经超过80Lm/W。因此,在照明设备中可以利用LED替换传统的卤素灯,例如MR16聚光灯。从传统的卤素灯过渡到高亮度LED可以大大降低功耗,     

Serial and Parallel FPGA-based Variable Block Size Motion Estimation Processors

H.264/AVC is the latest video coding standard adopting variable block size motion estimation (VBS-ME), quarter-pixel accuracy, motion vector prediction and multi-reference frames for motion estimation. These new features result in much higher computation requirements than previous coding standards. In this paper we propose a novel most significant bit (MSB) first bit-serial architecture for full-search block matching VBS-ME, and compare it with systolic implementations. Since the nature of MSB-first processing enables early termination of the sum of absolute difference (SAD) calculation, the average hardware performance can be enhanced. Five different designs, one and two dimensional systolic and tree implementations along with bit-serial, are compared in terms of performance, pixel memory bandwidth, occupied area and power consumption.

针对便携式应用的LED驱动解决方案

本文将总结部分常用LED驱动方案,然后详细探讨一些更新颖的LED驱功方法.     

Designing the optical interface of a transcutaneous optical telemetry link

Optical telemetry has long been an option for transcutaneous data transfer and has been used in various types of implanted systems. This telemetry modality and the efficiency of these optical links are becoming ever more important as higher bandwidth sources such as cortical recording arrays are being implemented in implanted systems. The design of the transmitter-skin-receiver interface (the "optical interface") is paramount to the operation of a transcutaneous optical telemetry link. This interface functions to achieve sufficient receiver signal power for data communication. This paper describes a mathematical analysis and supporting data that quantitatively describes the relationship between the primary interface design parameters. These parameters include the thickness of the skin through which the light is transmitted, the size of the integration area of the optics, the degree of transmitter-receiver misalignment, the efficiency of the optics system, and the emitter power. The particular combination of these parameters chosen for the hardware device will determine the receiver signal power and, therefore, the data quality for the link. This paper demonstrates some of the tradeoffs involved in the selection of these design parameters and provides suggestions for link design. This analysis may also be useful for transcutaneous optical powering systems.     

嵌入式x86：非PC设计的要旨？

那些考虑把PC构件用于非PC设计的人最好记住：把宝押在PC技术上并非完全正确。在这个体系结构方向经验丰富的同行们已经了解这一点。一方面,人们将受益于PC行业特有的迅猛创新速度,以及全球每年销售的数亿台PC带来的低价格。另一方面,这样的创新速度还导致了迅猛的报废速度,这对于那些生产周期超过六个月的系统而言可能会有问题!     

Real-time craving and mood assessments before and after smoking.

This study explored some quandaries concerning craving and mood as motivators to smoke. Craving and negative mood have long been associated with day-to-day smoking as two of the primary motivational forces behind the maintenance of the behavior, as well as significant barriers in smokers' attempts to quit. Craving remains a clinically relevant phenomenon, with most smokers describing craving as a troublesome problem when quitting. Smokers' self-reports of negative mood, as an antecedent for smoking, are so robustly reported that many models of nicotine dependence have incorporated a critical role for negative mood in maintaining smoking behavior. However, several naturalistic studies that collected mood ratings with hand held computers from smokers in real time, just before smoking a cigarette, have provided scant evidence that negative mood plays a major role in motivation to smoke. No study to date has examined craving and mood data as a consequence of smoking, that is, collecting the same data immediately after smoking. This study used personal digital assistants (PDAs) to collect craving and mood data immediately before smoking, immediately after smoking, and at random times of day. Nontreatment seeking smokers (N = 72) carried a PDA for an average of 10 days while they recorded their smoking behavior. Results showed that craving and negative mood ratings were lowest immediately after smoking compared with immediately before smoking and at random times of day. These findings suggest that smokers may be at least partially motivated to smoke to lower their craving and improve their mood states.     

Social support as a moderator of the relationship between recent history of depression and smoking cessation among lower-educated women.

We examined psychosocial mechanisms linking recent history of depression and subsequent short-term smoking cessation. Our sample included lower-educated women smokers who registered for a brief cessation intervention (registrant panel; n = 1,198), and a quasicontrol panel not participating in the intervention (population panel; n = 682). Women were surveyed by telephone every 6 months for a period of 2 years, measuring psychosocial variables (motivation, self-efficacy, perceived stress, and social support) and self-reported smoking status (7-day abstinence) at each point. In both panels, smoking rate and self-efficacy were strong independent predictors of subsequent cessation, but recent history of depression (as measured 6 months earlier) was not a significant predictor. However, among only the registrant panel, the effects of recent history of depression were significantly moderated by social support. Recently depressed women who had higher levels of perceived social support were as likely to quit subsequently as women who did not have a recent history of depression. The determinants of successful quitting among lower-educated women differ between those who seek assistance and those who do not.