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A novel design of trench in cladding with resonant ring is proposed in this paper. Performances of proposed fiber have been numerically investigated by the finite element method with a perfectly matched layer boundary. Simulation shows that the proposed fiber can provide high leakage loss ratio (776) between the high-order modes (HOMs) and fundamental mode (FM) which is beneficial to realize robust single-mode operation to enhance the transverse mode instabilities at a wavelength of 1080 nm. The HOMs suppression is better than the traditional step-index fibers (SIF). Furthermore, the bending loss can be reduced to about 0.0074 dB/m due to the trench in the cladding, and the effective mode area can achieve 744.49 μm2 at 15 cm bend radius, which is also beneficial to improve transmission efficiency. The advantage of an all-solid structure along with a much simpler fabrication process makes our approach very suitable for realizing very large mode area fibers for high power fiber laser application.

A novel bend-insensitive single mode fiber is proposed in this paper. A finite element method with a perfectly matched layer boundary is used to analyze characteristics of the mode field distribution, effective area and bending loss. To achieve the proposed fiber with a low bending loss, a symmetrical distribution of air holes on a doped trench is designed. The effects of structural parameters on the bending loss and effective area are discussed. The numerical results show that this structure can achieve a low bending loss and effective model area with smaller bend radius at a wavelength of 1550 nm. The bending loss is only 2.13 × 10−5 dB/m and the mode field diameter (MFD) is 8.71 μm, which can provide a good match with the single mode fiber (SMF). The simulation results show that the existence of air holes in the trenched layer can exist minimum point of bending loss with increasing the values of c, which is different from previous studies. Compared with a single mode fiber-28 (SMF-28) and a trench-assistant fiber (TAF), this structure still has an ultralow bending loss and a smaller effective area with a low-bend radius of 3 mm at a wavelength of 1550 nm. The proposed fiber may be preferable for optical connection.

This paper put forward a equivalent approach of high-density PCB assembly model, then use of sub-model on the local position of a second analytical solution. Firstly, the equivalent model, fine model and sub-model was established, and then modal analysis, random vibration analysis and sub-model analysis are performed. Comparison with the result data of the three models, it is verified the feasibility and correctness using of equivalent processing and sub-modeling techniques from the natural frequencies, mode, and stress distribution, maximum stress, maximum stress location, relative error of the maximum stress of the equivalent part. It is an effective method to analysis of high-density PCB assembly model. Finally, it is used the method to obtain the dynamic response of a particular high-density PCB assembly model under random vibration load.

A kind of MIMO networked control systems, in which the sensors and controller are interconnected by network and the state of control object is feedback to the controller and each loop is controlled at different sampling period, is studied in this paper. Supposed that the maximum network-induced delay is smaller than one sample period, its model is established. Based on estimation theorem of feature value from perturbation theory, the maximum allowable delay bounds subject to asymptotic stability for systems is derived. Simulation example shows that the stability criterion is feasible.

To aim at the problem of networked control system which is the hotspot of research and application nowadays, a method with the object controlled by switched output feedback is proposed in this paper. It is that the feedback signal is used for the calculation of the control signal when the delay induced by the network is less than sampling period; And when the feedback signal cannot arrive at the controller in time, a signal estimated by LS-ARX (autoregressive model with exogenous) is used for feedback signal in calculating the control signal. The structure of relevant algorithm is designed, and a practical example that a DC motor is controlled through CAN network with periodic and burst interference is given in this paper. The results by simulated on the platform of TRUETIME shows that the influence to the performance of output by the interference is low and the method has good reference in practical application.

To aim at the problem of networked control system which is the hotspot of research and application nowadays, a method of self-adaptive prior scheduling of mult-tasks is presented. It is that the prior of each task is determined by its evaluated factors, and then the tasks are dynamicallly scheduled by their priors in the single-controller. The shecduling rules and the structure of scheduling algorithm are given in this paper. A practical example that the DC motors of X, Y and Z axis of a simple three-axis gear machine tool are controlled by single-controller and through a network is given in this paper, where the the controlling error and the sampling period and the importance of each task is adopted as its assessing factors to calculate its prior dymanically. The results of simulation on the platform of TRUETIME shows that the mentod presented in this paper is correct and practical.

Four process parameters including, the pad length, the pad width, the stencil thickness and the stand-off, are chosen as four control factors, and by using an L 25 (56) orthogonal array, the no-fillet chip component solder joints shapes with 25 different process parameters combinations are established. And then all the shape prediction models of the 25 solder joints are built through the Surface Evolver soft, after that, the finite element analysis models are set up by converting the above ones. Afterwards, a non-linear finite element analysis on the no-fillet chip component solder joints under thermal cycles are performed by using ANSYS soft, and the thermal fatigue lifes of them are achieved through Coffin-Manson equation. Finally the variance analysis was performed based on the above lifes figures. The research show that with 95% confidence the stand-off has a significant effect on the reliability of the no-fillet chip component solder joints, whereas the pad length, the pad width and the stencil thickness have little effects on the reliability of the ones.

The thermal mathematical model under intensive convection in lead-free reflow soldering process is constructed for surface mounted assemblies, and the heat conduction governing equation, initial condition and boundary condition are made. A thermal mathematical model of SMA is transformed into solid model which can be analyzed by the thermal analysis software FLOTHERM. Then by defining the reasonable boundary condition and model simulating analysis, the thermograph contour map and profile for the SMA are obtained. Using the data relevant to simulation reflow profile and orthogonal experiment design to set up the factor effect table, the degree of the critical parameters of lead-free reflow soldering process affecting the key index of thermal profile would be obtained. The results show that the heating rate is mainly affected by the conveyer belt speed, temperature of heating zone No.6 and No.2; the maximum temperature is mainly affected by the conveyer belt speed, temperature of heating zone No.6 and No.7; and the soldering time of extension melting point temperature is mostly affected by conveyer belt speed.

In the thermal design of IC (integrated circuit) device, the traditional single varying parameter appraisal method for thermal analysis has ignored the mutual influence and interaction between parameters, without a multiparameter synthetical design and optimization, now it does not meet the reality and design demand any longer that high density IC device works with the multiparameter influence and interaction and high heat reliability.In this paper, with QFP (quad flat package) device taken as an example, the analysis method of the combination of the orthogonal experimental method and response surface method is applied to the analysis and evaluation for IC device heat characteristic. This one can take it into account roundly that some design parameters work commonly on the package heat performance of the IC device, sequentially bring the multiparameter and synthetical optimization heat design into reality. So it is a perfect and applied method for the heat characteristic evaluation and heat design for IC component.

The electronic packaging and assembly technology is developing to high-density, fine-pitch and micromation. At the same time, an ever increasing need has developed for a lead-free solder joint interconnection due to the restrictions on the use of lead, and the upward spiraling market demand of green products. As a result the reliability of solder joint has attracted a great deal of attention, especially the lead-free solder joint. In this study, the three-dimensional (3D) shape of bottom leaded plastic (BLP) solder joints are predicted by the surface evolver software tool based on the minimum energy theory. And the geometrical models for reliability analysis are built directly from 3D shape models of BLP solder joints predicted by surface evolver using interface software of model converting. The lead-free solders considered are 96.5Sn3.5Ag and 95.5Sn3.8Ag0.7Cu. The 63Sn37Pb and 62Sn36Pb2Ag leaded solders are also considered to establish baselines. The Anand unified viscoplastic constitutive law is applied to represent the viscoplastic deformation behaviors for these solder alloys. Time-temperature-dependent nonlinear analysis of BLP solder joints on printed circuit board (PCB) assemblies subjected to thermal cycling conditions are presented using ANSYS finite element simulation software tool. The stress distribution, strain distribution and failure location of BLP-I and BLP-II solder joints are presented. The comparisons of Von Mises stress time history and equivalent plastic strain time history between different solder joints are provided also. The thermal fatigue life of BLP solder joints is predicted by the modified Coffin-Manson model based on the equivalent plastic strain range. Also, the effects of various solders and solder joint shape on BLP solder joint reliability are provided

Agency organization is a bridge of enterprise collaborative manufacturing; small and medium scale enterprise (SME) is the main body of collaborative manufacturing. So it is necessary and urgent to build SME collaborative manufacturing system based on agency organization services. In this paper, based on analysis of characteristics of SME, five layers collaborative manufacturing system including physics layer, resource layer, pattern layer, agency organization service layer and application layer was built. Organization pattern and coordination pattern based on agency organization services were analyzed too. Agency organization collaborative manufacturing information services-oriented technology founded on SOA (services-oriented architecture) was studied. At last, software lease platform of agency organization serving for SME were accomplished based on remote terminal services.