摘要：To design effective and easy-to-manufacture conductive heat channels, a heuristic method by emulating the natural branch systems is suggested. The design process of the method is divided into two steps, which are the principal channel design and the lateral channel design. During the process, the width of each channel is controlled by the bifurcation law, and the end point of the channel is located at the point with the maximum temperature while the start points of the principal channel and the lateral channel are respectively determined by the location of the heat sink and the law of the minimum thermal resistance. Four design examples with different boundary conditions are studied by the suggested method, and the design results are compared with that of the traditional structural topology optimization method. Not only lower maximum temperature and relatively uniform distribution of temperature are obtained by the suggested method, but also straight channels are achieved without gray element, which is easy to manufacture. The suggested method inspired by the natural branch systems can provide an effective solution for heat channel design in the heat dissipation structures.

摘要：A series of novel fluorine-containing acrylates 6a-6g were synthesized via the condensation of ethyl cyanoacetate and trifluoroacetic anhydride, followed by chloridization and the coupling reaction with amines. These new compounds exhibited some biological activity as preliminary bioassay indicated. A plausible reaction mechanism was outlined and discussed.

摘要：This study presents two multimode stepped-impedance structures to design single-and dual-band filters. Transmission zeroes are introduced for the single-band filter by using dual-mode stepped-impedance resonators. The single-band filter with high selectivity is centered at 6.02 GHz and has a fractional bandwidth （FBW） of 25.6%. Four stubs （two low frequency and two high frequency ones） are connected to the rectangular patch in the center to construct a quadruple-mode resonator. The independent conditions of the center frequencies of the high and low bands of the resonator are analyzed. A dual-band filter, which operates at 1.53 GHz and 2.44 GHz with FWBs of 12.1% and 14.1%, respectively is designed. The single-and dual-band filters are both fabricated with double-sided YBCO films and they can be used in mobile and satellite communications.

摘要：Component sequence preservation is an intrinsic requirement in typical engineering applications, such as deployable chain-likestructures, 3D printing structures with contour-parallel toolpaths, additive manufacturing of continuous fibre-reinforcedpolymer structures, customized stents, and soft robotics parts. This study presents a feature-driven method that preservescomponent sequences accounting for engineering requirements. The chain-of-bars design variables setting scheme is developedto realize the sequential component’s layout, which sets the current bar’s end point as the next bar’s start point. The total lengthof the printing path is constrained to reduce the consumption of material accurately. Also, the angle between adjacent bars isconstrained to avoid sharp angles at the turning point of the 3D printing path. Next, the sensitivity analysis considering theinter-dependence of substructures is performed. Several numerical examples are given to demonstrate the validity and merits ofthe proposed method in designing structures preserving component sequences.

摘要：This paper presents a new simple method of implicit time integration with two control parameters for solving initial-value problems of dynamics such that its accuracy is at least of order two along with the conditional and unconditional stability regions of the parameters. When the control parameters in the method are optimally taken in their regions, the accuracy may be improved to reach of order three. It is found that the new scheme can achieve lower numerical amplitude dissipation and period dispersion than some of the existing methods, e.g. the Newmark method and Zhai＇s approach, when the same time step size is used. The region of time step dependent on the parameters in the new scheme is explicitly obtained. Finally, some examples of dynamic problems are given to show the accuracy and efficiency of the proposed scheme applied in dynamic systems.

摘要：The three-dimensional discontinuous deformation analysis(3D-DDA) is a promising numerical method for both static and dynamic analyses of rock systems. Lacking mature software, its popularity is far behind its ability. To address this problem, this paper presents a new software architecture from a software engineering viewpoint. Based on 3D-DDA characteristics, the implementation of the proposed architecture has the following merits. Firstly, the software architecture separates data, computing, visualization, and signal control into individual modules. Secondly, data storage and parallel access are fully considered for different conditions. Thirdly, an open computing framework is provided which supports most numerical computing methods; common tools for equation solving and parallel computing are provided for further development. Fourthly, efficient visualization functions are provided by integrating a variety of visualization algorithms. A user-friendly graphical user interface is designed to improve the user experience. Finally, through a set of examples, the software is verified against both analytical solutions and the original code by Dr. Shi Gen Hua.

摘要：From stable carbon isotope analysis of tree-rings of chinese pine (Pinus tabulaeformis) from Mt. Helan, China, we found that high-δ13C values were related to high mean temperatures from June to August (T 68), and Iow-δ13C values corresponded to low T 68. From these data, a transfer function has been used to reconstruct summer temperatures (T 68) for the Mt. Helan region. The explained variance of reconstruction is 34.9% (F=15.01, p<0.001). The time period containing the highest summer temperatures in northern China (late 1920-1930s) was confirmed by our reconstruction. The data indicate that there is a tele-connection between summer temperatures in Mt. Helan area and sea-surface-temperatures in the tropical Pacific. The extreme low temperature periods around the years of 1920 and 1947 for Mt. Helan region correspond well to the cold climate in the tropical Pacific. Along with other analyses, this suggests that climate variations in the Mt. Helan region are driven not only by local events, but also by the global climate. Significant periodicities appearing in the reconstruction are 2.56 and 2.63 years.

摘要：A low noise distributed amplifier consisting of 9 gain cells is *** chip is fabricated with 0.15-μm GaAs pseudomorphic high electron mobility transistor（PHEMT） technology from Win Semiconductor of Taiwan.A special optional gate bias technique is introduced to allow an adjustable gain control range of 10 dB.A novel cascode structure is adopted to extend the output voltage and *** measurement results show that the amplifier gives an average gain of 15 dB with a gain flatness of±1 dB in the 2-20 GHz *** noise figure is between 2 and 4.1 dB during the band from 2 to 20 *** amplifier also provides 13.8 dBm of output power at a 1 dB gain compression point and 10.5 dBm of input third order intercept point（IIP3）,which demonstrates the excellent performance of *** power consumption is 300 mW with a supply of 5 V,and the chip area is 2.36×1.01 mm^2.

摘要：Modularized circuit designs for chaotic systems are introduced in this ***,a typical improved modularized design strategy is proposed and applied to a new hyper-chaotic system circuit *** this paper,the detailed design procedures are *** simulations and physical experiments are conducted,and the simulation results are compared with Matlab simulation results for different system parameter *** results are consistent with each other and they verify the existence of the hyper-chaotic attractor for this new hyper-chaotic system.

摘要：The instability of soil bank slopes induced by freeze-thaw cycles at the northern foot of Tianshan Mountain is very *** failure not only caused a large amount of soil erosion,but also led to serious reservoir sedimentation and water quality degradation,which exerted a lot of adverse effects on agricultural production in the local irrigation *** on field investigations on dozens of irrigation reservoirs there,laboratory tests were carried out to quantitatively analyze the freeze-thaw effect on the soil engineering characteristics to reveal the facilitation on the bank slope *** results show that the softening characteristics of the stressstrain curves gradually weaken,the effective cohesions decline exponentially,the seepage coefficients enlarge,and the thermal conductivities decrease after 7 freeze-thaw *** freeze-thaw effect on the specimens with low confining pressures,low dry densities and high water contents is more *** water migration and the phase transition between water and ice result in the variations of the soil internal microstructures,which is the main factor affecting the soil engineering *** water supply and the alternation of positive and negative temperatures at the reservoir bank slopes in cold regions make the water migration and phase transition in the soil very *** is easy to form a large number of pores and micro cracks in the soil freezing and thawing *** volume changes of the soil and the water migration are difficult to reach a dynamic balance in the open ***-term freeze-thaw cycles will bring out the fragmentation of the soil particles,resulting in that the micro cracks on the soil surfaces are developing *** soil of the bank slopes will fall or collapse when these cracks penetrate,which often happens in winter there.