Design considerations for Rowland circle gratings used in photonicintegrated devices for WDM applications

Design issues of photonic integrated devices for WDM applications based on Rowland circle gratings have been studied. Effects of grating period, diffraction order, grating aperture (size), and Rowland circle size on device performance are discussed. The point spread function of a typical Rowland circle grating is evaluated numerically which yields an optical image (spot) size of several microns in diameter. Our study shows that there is a tradeoff between channel dispersion and feedback efficiency in choosing the grating period when a Rowland circle grating is used as the wavelength-selective element for a parallel-waveguide-type wavelength division multiplexing device     

Performance and reliability enhancement for CVD tungsten polycidedCMOS transistors due to fluorine incorporation in the gate oxide

The impacts of CVD tungsten polycide (WSi_x) on MOSFET performance and reliability are studied in this letter. The WSi_x process is shown to enhance the S/D lateral extent for both N- and P-channel devices via C_GD and L_eff measurements, confirming previous suspicion. This enhanced S/D extent is found to be easily modulated by drain-to-gate bias, which is favorable for achieving both higher drive currents and higher S/D punch-through voltages than those of non-WSi_x devices. Both electron and hole mobility for the WSi_x device are also slightly higher and closer to the published data compared to the non-WSi_x case. These effects together yield about >5% improvement for nMOSFET and >10% improvement for pMOSFET in drive current at a given punch-through voltage. The channel hot-electron lifetime for the n-channel WSi_x device is about 10 times higher than that of the non-WSi_x one. These enhancements in both performance and reliability make the WSi_x device very attractive fog VLSI CMOS technologies     

Design of a product quality control system based on the use of data mining techniques

In recent years industries have increasingly used customer relationship labor in management as a tool to improve their position in the marketplace. This research involves using a data warehouse, decision-tree-based data mining, and neural network pattern classification analysis to isolate the causes of non-conformity in IC packaging. The correctness of the classification analysis produced using the two methods is compared. Our objective is to establish an information analysis system, that is able to quickly identify the causes of problems thereby reducing the time taken to solve quality-related problems. It is shown that predictions made about the target group using decision tree analysis are more accurate than those made by neural network classification, indicating that decision tree analysis is an effective means of classification analysis of a company's quality problems.     

微型灌注桩托换技术在地基基础加固工程中的应用

因场地淤泥等软土层深厚,在填方荷载作用下,软弱土层产生固结沉降,引起局部构筑物的不均匀沉降,发生结构破坏。采用微型灌注桩加固满足现场各个限制条件的要求,达到了加固目的。     

Flammability and thermal stability studies of ABS/Montmorillonite nanocomposite

Acrylonitrile–butadiene–styrene (ABS)/montmorillonite nanocomposites have been prepared using a direct melt intercalation technique by blending ABS and organophilic clay of two different particle sizes: OMTa (5 µm) and OMTb (38 µm). Their structure and flammability properties were characterized by X‐ray diffraction, high resolution electronic microscopy (HREM), thermogravimetric analysis (TGA) and cone calorimeter experiments. The results of HREM showed that ABS/5 wt% OMTa nanocomposite was a kind of intercalated–delaminated structure, while ABS/5 wt% OMTb nanocomposite was mainly an intercalated structure. The nanocomposites showed a lower heat release rate peak and higher thermal stability than the original ABS by TGA and cone calorimeter experiments. Also, the intercalated nanocomposite was more effective than an exfoliated–intercalated nanocomposite in fire retardancy. Copyright © 2003 Society of Chemical Industry     

Hybrid switching and p-routing for optical burst switching networks

One promising switching technology for wavelength-division multiplexing optical networks is optical burst switching (OBS). However, there are major deficiencies of OBS. (1) The delay offset between a control message and its corresponding data burst is based on the diameter of a network. This affects network efficiency, quality-of-service, and network scalability.( 2) OBS adopts one-way resource reservation scheme, which causes frequent burst collision and, thus, burst loss. We address the above two important issues in OBS. In particular, we study how to improve the performance of delay and loss in OBS. To reduce the end-to-end delay, we propose a hybrid switching scheme. The hybrid switching is a combination of lightpath switching and OBS switching. A virtual topology design algorithm based on simulated annealing to minimize the longest shortest path through the virtual topology is presented. To minimize burst collision and loss, we propose a new routing algorithm, namely, p-routing, for OBS network. The p-routing is based on the wavelength available probability. A path that has higher available probability is less likely to drop bursts due to collision. The probability-based p-routing can reduce the volatility, randomness, and uncertainty of one-way resource reservation. Our studies show that hybrid switching and p-routing are complementary and both can dramatically improve the performance of OBS networks.     

Apply geometric duality to energy-efficient non-local phenomenon awareness using sensor networks

A powerful concept to cope with resource limitations and information redundancy in wireless sensor networks is the use of collaboration groups to distill information within the network and suppress unnecessary activities. When the phenomena to be monitored have large geographical extents, it is not obvious how to define these collaboration groups. This article presents the application of geometric duality to form such groups for sensor selection and non-local phenomena tracking. Using a dual-space transformation, which maps a non-local phenomenon (e.g., the edge of a half-plane shadow) to a single point in the dual space and maps locations of distributed sensor nodes to a set of lines that partitions the dual space, one can turn off the majority of the sensors to achieve resource preservation without losing detection and tracking accuracy. Since the group so defined may consist of nodes that are far away in physical space, we propose a hierarchical architecture that uses a small number of computationally powerful nodes and a massive number of power constrained motes. By taking advantage of the continuity of physical phenomena and the duality principle, we can greatly reduce the power consumption in non-local phenomena tracking and extend the lifetime of the network.