智能手机操作系统群雄并起

近年来,随着全球移动数据业务使用量的迅猛增长,智能手机销量不断攀升。代表不同市场阵营的智能手机操作系统竞争日益激烈。笔者在回顾市场上主流操作系统形成现今市场地位的历史原因同时,对其未来的发展机遇逐一作了分析,在此基础上,对未来智能手机操作系统的市场格局做出了预测。     

Development of CNPC’s Drilling Business

With further exploration and development of oil and gas fields both at home and abroad,complicated geological conditions,poor quality of reserves and abominable working environment,drilling business,the largest of upstream petroleum     

Occurrence and characteristics of Vibrio vulnificus in retail marine shrimp in China

Vibrio vulnificus is a gram-negative bacterium that naturally occurs in estuarine waters and marine environment. Consumption of seafood contaminated with V. vulnificus or exposure to the contaminated water causes septicemia, gastroenteritis or wound infections in humans. This study aimed at identifying the prevalence of V. vulnificus in shrimps in Chinese seafood market. From June to September 2009, 239 samples encompassing six shrimp species were collected from ten cities in China. To quantify the prevalence and the levels of V. vulnificus in shrimps, the most probable number (MPN) method was used combining with the polymerase chain reaction (PCR) which was used to classify the isolates by detecting V. vulnificus hemolysin gene (vvhA). One hundred and forty out of 239 samples were positive for V. vulnificus, with the geometric mean level at 153.3 MPN/g. The prevalence and levels of V. vulnificus in shrimps varied in different geographic areas, with the values for the samples in the South cities (179.6 MPN/g) remarkably higher than that in the North cities (7.6 MPN/g). In addition, we found that 61.7% (79/128) of the V. vulnificus positive samples contained C-type (Clinical) strains and 8 contained E-type (Environmental) strains. The antimicrobial susceptibility of the isolates to 12 antibiotics was tested as well. Most of the 169 isolates remained susceptible to the majority of antimicrobials tested, whereas some strains tend to be less sensitive to amikacin, ampicillin, tetracycline and gentamicin. In conclusion, V. vulnificus is commonly found in retail marine shrimp in Chinese seafood market, and most of the shrimp samples contained C-type strains, which may pose a potential threat to human health.     

Molecular Dynamics Study of the Structural and Mechanical Properties of Skutterudite CoSb<Subscript>3</Subscript>: Surface Effect

Molecular dynamics simulations of the structural and mechanical properties of single-crystalline CoSb₃ have been carried out at room temperature. Special emphasis was given to the surface effect. Four different boundary conditions were applied to represent a wide range of surface-atom fractions. The LAMMPS program in conjunction with a multibody potential was employed. First, free relaxation was performed to obtain the corresponding stable configurations. The atomic rearrangements and energy distributions were observed. Then, uniaxial tensile deformation was simulated at a constant strain rate. The stress–strain responses and structural evolutions were examined during the process. Comparison of simulation results between different boundary conditions was carefully made. It was found that, when the scale of the single-crystalline CoSb₃ model becomes nanometric and the fraction of the surface atoms increases, the mechanical performance becomes substantially worse. Nonetheless, the deformation mechanism and intrinsic mechanical nature are very similar.     

Power-efficient M-ary PSSK Communications with Uncertain Phase Errors

M-ary phase-silence-shift-keying (PSSK), one of power-efficient modulation schemes, has enhanced symbol error rate (SER) performance by 6 dB compared with that of the conventional phase-shift-keying (PSK). Phase tracking problem of the PSSK with phase-locked-loop (PLL) is discussed in this paper. Capacity of the PSSK for the additive white Gaussian noise (AWGN) channel and Rayleigh fading channel is analyzed. Capacity loss of the PSSK due to the PLL is small, which tells us that the PSSK demodulator can be practically implemented.     

润滑油监测技术的发展方向

简单介绍了润滑油监测技术,润滑油监测技术正向在线监控,微型化,多功能,可视化,无损检测,智能化和远程诊断的方向发展.     

基于Pro/E的手机结构数字化设计

手机已经成为人们日常生活必不可少的通信工具,现代手机除了不断的更新、丰富使用功能外,手机产品的外形结构变化也越来越快,以满足人们个性化的需求。因此也对手机设计厂家提出更快的设计要求,为了保证手机设计的质量和速度,采用基于Pro/E软件的自顶向下设计方法,如果客户要求的时间更短则可以利用协同设计的方法来满足客户需求。     

Baushinger’s Effect in Wear of Materials

The response of Cu–40%Zn alloy to wear during unidirectional and bidirectional abrasion processes was investigated. It was observed that the mass loss of the alloy decreased as the number of times of changing the sliding direction was increased. Corresponding to this decrease in mass loss, hardness of the worn surface increased initially and then decreased. Cracking in the surface layer was analyzed to get an insight into the mechanism involved. Results of the study suggest that Baushinger’s effect played a role when the sliding direction was alternated.     

A Follow-up Study on Bauschinger’s Effect in Bidirectional Wear of Cu-40%Zn against Different Types of Counter-Face

Previously, we demonstrated a decrease in wear loss of Cu-40%Zn against a steel wheel during bidirectional sliding ascribed to Bauschinger’s effect associated with diminished strain-hardening. However, the situation changed when the alloy was worn by a ceramic-grinding wheel. It was observed that the mass loss continuously increased with reversal of the sliding-direction although the corresponding hardness of worn surface also decreased. In this case, Bauschinger effect still functioned but the failure mode varied, leading to the different trend of response to wear against the ceramic-grinding wheel in comparison with that against the steel counter-face.