摘要：玻璃形成能力是金属玻璃领域中长期存在的问题,它极大地限制了金属玻璃的最大铸造尺寸和广泛应用.在本研究中,我们报道了超声辅助快速冷焊接块体金属玻璃的方法.在不需要焊料的情况下,通过20,000赫兹的高频振动实现了不同组分金属玻璃的结合,并且保证了金属玻璃的非晶态特性.超声技术有低温低压快速焊接的优点,其中焊接温度接近室温,压强小于1 MPa,焊接时间小于1 s.根据观察到的现象,随着金属玻璃氧化层的不断破裂,金属玻璃被超声振动激活并通过破裂的氧化层扩散到基体中,同时超声振动加速了扩散的过程,最终实现金属玻璃界面的稳定结合.这种普适性的超声辅助焊接工艺可以实现金属玻璃的大块化,以及不同组分的非晶态复合材料与新性能的设计.

摘要：A tri-port MIMO antenna designed for Micro/Pico-Cell application is *** is based on printed elements with X-shaped arms,which are oriented to 0°,120° and240° in the azimuth *** arms of these elements are connected,with which a selfdecoupled structure is *** mutual coupling between adjacent elements is below-15 ***,it size is compact and bidirectional radiation patterns with around 4dBi Gain and 92° 3dB beam width is achieved,which can provide good pattern diversity and full azimuth coverage in real applications.

摘要：这份报纸拿在作为主要科学问题设计构造和生态系统变化之间的相互作用。基于 DPSIR ( Drive-Press-State-Impact-Response )框架，这研究分析在从开车，出版社，状态，影响和反应的方面设计构造和生态系统变化之间的相互作用的通匝，向前带相互作用模型，相互作用情形分析方法和相互作用索引(开车反应索引， IIDR ，开车影响索引， IIDI ，影响反应索引，红外，影响索引， IIII )，并且预付相应计算模型和相互作用索引 sy 并且也，这份报纸采用不同相互作用索引到尊重影响在上和对设计建设的反应，并且作为例子在纵的范围峡区域(LRGR ) 拿 Manwan 水力发出的电力车站和道路交通建设分析并且验证相互作用模型。由建设的结果和 Manwan 水力发出的电力的操作的系统的分析，车站是分别地 3.67， 3.92， 14.35 和 0.35。没有在相互作用系统，和利用的通匝元素的显著变化水力发出的电力车站基于想象有益于地区性的环境和社会的持续发展没有考虑环境费用，散开效果，潜在的否定效果和潜力，水力发出的电力的回答驻扎建设。通过一些案例研究，我们造了的相互作用模型在相互作用显示出很好的实际价值量的分析并且相互作用索引系统构造。

摘要：In the present work,a principle of equipartition of entransy dissipation(EoED) for heat exchanger design is established,which says that for a heat exchanger design with given heat duty and heat transfer area,the total entransy dissipation rate reaches the minimum when the local entransy dissipation rate is uniformly distributed along the heat *** the heat transfer coefficient is unfixed,the total entransy dissipation obtained by the EoED principle is less than that obtained by the principle of equipartition of temperature difference(EoTD).Furthermore,the exchanger effectiveness obtained by the EoED principle is larger than that obtained by the EoTD *** the heat transfer coefficient is fixed,the EoED principle is equivalent to the EoTD *** show that the equipartition of entropy production(EoEP) and EoED principles give rise to difference in entropy generation and entransy dissipation for a heat exchanger optimization *** discrepancies are caused by distinct features of entropy production minimization and entransy dissipation minimization principles,the former is to optimize the design of heat exchanger by making the lost available work minimum,while the latter is not involved with heat-work *** is found that the entropy generation number is not suitable for evaluating heat exchanger performance,since it directly depends on the inlet and outlet temperatures of working *** the contrary,the entransy dissipation number is not directly related to the inlet and outlet temperatures of working ***,the entransy dissipation number is more suitable for serving as a criterion to evaluate heat exchanger performance.

摘要：In multi-hop cognitive radio networks (CRNs), the heterogeneous environment increases the complexity of common control channel (CCC) formation and routing protocol design. In this paper, we consider the on-demand routing protocol transmits over CCC. However, since CR transceivers (secondary users) have different available channel sets and it must vacate the licensed channel when a primary user arrives, forming a CCC becomes a main challenge in routing protocol design for CRNs. Our proposed CCC formation algorithm is based on a spectrum-tree structure, which consists of all cluster heads in CRNs. The cluster heads are with smaller moving range and lower mobility, and also act as a router in the whole network which maintains information of its cluster. Hence, a route is constituted in part by a set of cluster-head identity (ID) numbers, which represent the specific cluster heads the path traverses, and in part by a set of member nodes ID numbers, which are included in the clusters containing the source and destination nodes. Due to high mobility and dynamic available spectrum, we define the stability parameters of path as two parts. One stability parameter is mobility factor, which represents the probability that a pairwise node can keep in communication range for the next flow transmission. The another stability parameter is spectrum opportunistic (SOP) factor, which represents the probability that a pairwise links can obtain the assigned spectrum band for the next flow transmission. Simulation results show that CCC formation algorithm produces a high probability of CCC formation, and the proposed routing protocol performs better than typical routing protocols. Copyright © by HIGH TECHNOLOGY LETTERS PRESS.

摘要：The objective of the present paper is to study the sweep effect on the blade design performance of a transonic compressor *** baseline to be modified and swept is a designed well efficient transonic single rotor compressor. The first part of the present study is concerning the sweep effect with straight leading *** this case fixing the hub section the swept blade is formed by tilting the leading edge with whole blade forwards and backwards *** second part is to use an optimization strategy with simple gradient-based optimum-searching method and multi-section blade parameterization technique to search and generate an optimal swept rotor with curved arbitrary leading *** adiabatic efficiency is a little bit greater than that of the reference un-swept rotor.

摘要：Both reverse osmosis(RO) and nanofiltration(NF) membranes have been increasingly used for water purification and desalination. However, the salt rejection of NF membranes is quite different from that of RO membranes,which makes a significant distinction in their process designs. This work started from the performance investigation of a single NF membrane element and then focused on the process design of the NF system for surface water treatment. In experimental tests, it was found that the observed rejection of the NF element becomes nearly constant when the concentrate flow is large enough, while the membrane flux of the NF element is quite stable regardless of the water flow across the membrane surface. These findings can be used to instruct the process design of the NF system for surface water treatment. In process design, a two-stage arrangement is sufficient for the NF system to reach the highest water recovery, while the RO system requires a three-stage arrangement.

摘要：The inlet attack angle of rotor blade reasonably can be adjusted with the change of the stagger angle of inlet guide vane (IGV); so the efficiency of each condition will be affected. For the purpose to improve the efficiency, the DSP (Digital Signal Processor) controller is designed to adjust the stagger angle of IGV automatically in order to optimize the efficiency at any operating condition. The A/D signal collection includes inlet static pressure, outlet static pressure, outlet total pressure, rotor speed and torque signal, the efficiency can be calculated in the DSP, and the angle signal for the stepping motor which control the IGV will be sent out from the D/A. Experimental investigations are performed in a three-stage, low-speed axial compressor with variable inlet guide vanes. It is demonstrated that the DSP designed can well adjust the stagger angle of IGV online, the efficiency under different conditions can be optimized. This establishment of DSP online adjustment scheme may provide a practical solution for improving performance of multi-stage axial flow compressor when its operating condition is varied.

摘要：Most transmission gratings in the x-ray region work with their first orders and dispersion is limited by the line density achievable with current fabrication technology. We present a novel design of a two-dimensional x-ray transmission grating. The grating works with higher dispersion using its second orders, and the influence from first and third orders can be suppressed. A grating according to the novel design is fabricated and its diffraction performance is tested in comparison with a traditional x-ray transmission grating with the same line density. The novel grating could be especially useful when high dispersion is desired while the fabrication of high-density gratings becomes more difficult.

摘要：Dunhuang murals are gems of Chinese traditional art. This paper demonstrates a simple, yet powerful method to automatically identify the aesthetic visual style that lies in Dunhuang murals. Based on the art knowledge on Dunhuang murals, the method explicitly predicts some of possible image attributes that a human might use to understand the aesthetic visual style of a mural. These cues fall into three broad types: ① composition attributes related to mural layout or configuration; ② color attributes related to color types depicted; ③ brightness attributes related to bright conditions. We show that a classifier trained on these attributes can provide an efficient way to predict the aesthetic visual style of Dunhuang murals.