Utilization of self-injection Fabry–Perot laser diode for long-reach WDM-PON

In this investigation we propose and demonstrate a wavelength widely tunable laser source employing a self-injected Fabry–Perot laser diode (FP-LD) for long-reach wavelength-division-multiplexed passive optical network (WDM-PON). By using a tunable bandpass filter and an optical circulator inside the gain cavity, a stable and single-longitudinal-mode (SLM) laser output is achieved. Besides, the proposed laser sources are directly modulated at 2.5 Gb/s for both downlink and uplink transmissions of 85 km single mode fiber (SMF) in PON without dispersion compensation.     

A Bayesian Probabilistic Approach for Crack Characterization in Plate Structures

Abstract: This article explores the possibility of using a Bayesian probabilistic approach for the detection of cracks in thin plate structures, utilizing measured dynamic responses at only a few points on the plate. Existing laser scanning or shearography based crack detection methods are applicable only when measurement at the region near the defect is possible. These types of techniques are important in providing information, in addition to that obtained through visual inspection, for the purpose of structural health monitoring. Because of the global nature of the vibration characteristics of structural systems, this article puts forward a crack detection approach that can be applicable with only a few sensors and when the sensor locations are not close to the crack. This kind of method is particularly valuable as it can be applied when visual inspection is not possible (e.g., part of the plate is obstructed and is not assessable by inspectors). Owing to the problems of measurement noise and incomplete measurement (i.e., only a limited number of measurement points are employed and high‐mode information is lost because of the digitization of the signal and measurement noise), the results of crack detection as an inverse problem contain uncertainties. To explicitly handle such uncertainty, the proposed crack detection method follows the Bayesian statistical system identification framework. Rather than pinpointing the crack parameters (i.e., the crack location, length, and depth), the posterior probability density function (PDF) of the crack parameters is calculated to quantify the confidence level of the identified results, which is extremely important for engineers when they make judgments about remedial works. This article reports the theoretical development of the modeling of a cracked plate and a crack detection method together with numerical verification of the proposed method. The case study results are very encouraging, and indicate that the proposed method is feasible.     

Posttraumatic stress disorder patients' readiness to change alcohol and anger problems.

Notes that recovery from combat-related posttraumatic stress disorder (PTSD) is often complicated by unacknowledged problems with alcohol and anger. 102 males combat veterans (aged 42–63 yrs) entering a residential PTSD rehabilitation program completed University of Rhode Island Change Assessment and process-of-change questionnaires based on J. O. Prochaska and C. C. DiClemente's transtheoretical model (TTM; J. O. Prochaska et al, 1992). Separate assessments were made for alcohol abuse and anger control. Four motivational subtypes were identified for both problems. Motivation to change alcohol problems was independent of that for anger. Relative to less-motivated peers highly motivated patients were more like to spontaneously identify alcohol or anger as problems in their life and made greater use of change strategies specified by the TTM. These results support extension of the TTM to anger management and to PTSD management. Treatment implications are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nanoparticles of latexes from commercial polystyrene

Nanoparticles of polystyrene (PS) (Mw = 1.0-3.0 x 10(6) g/mol) latexes have been successfully prepared from their respective dilute PS (commercial) solutions in cyclohexane, toluene/methanol, or cyclohexane/toluene at each theta temperature. The cationic surfactant cetyltrimethylammonium bromide (CTAB) was used to stabilize the formed PS latex particles. By varying different concentrations of CTAB and PS solution of various Mw, we have successfully produced, for the first time, stable bluish-transparent latex particles ranging from about 10 to 30 nm in diameter (Dw). The number of polymer chains per latex particle (np) is directly proportional to the volume occupied by each latex particle and hence associated to its Dw. The characteristics of these preformed PS latex particles are quite similar to those obtained from the microemulsion polymerization of styrene as reported in literature. These PS latex particles could be further grown by seeding polymerization of styrene to about 50 nm (Dw) with a monodisperse size distribution of Dw/Dn = 1.08.     

Design of a RFID case-based resource management system for warehouse operations

In the past, the selection of resources to execute various warehouse operation services was done solely by experts. In this paper, a RFID-based Resource Management System (RFID-RMS) is designed to help users to select the most suitable resource usage packages for handling warehouse operation orders by retrieving and analysing useful knowledge from a case-based data warehouse for solutions in both time saving and cost effective manner. In addition, a pure integral-linear programming model using a branch and bound algorithm to define the optimum travel distance of forklifts is also developed and embedded in the proposed system. The proposed system, which is suitable for usage in a warehouse operation environment, enhances the effectiveness in formulating resource usage package and managing resource operation by integrating the Radio Frequency Identification (RFID), case-based reasoning (CBR) technologies and the programming model for forklift route optimization. Through applying RFID-RMS in the GENCO Distribution System, a multinational logistics company, the utilization of warehouse resources is expected to be maximized while work efficiency will be greatly enhanced.     

Improvement of borrowing channel assignment for patterned traffic load by online cellular probabilistic self-organizing map

This paper describes an improvement of borrowing channel assignment (BCA) for patterned traffic load by using the short-term traffic prediction ability of cellular probabilistic self-organizing map (CPSOM). The fast growing cellular mobile systems demand more efficient and faster channel allocation techniques today. In case of patterned traffic load, the traditional BCA methods are not efficient to further enhance the performance because heavy-traffic cells cannot borrow channels from their neighboring cells with light or medium traffic that may have unused nominal channels. The performance can be increased if the short-term traffic load can be predicted. The predicted results can then be used for channel re-assignment. Therefore, the unused nominal channels of the light-or-medium-traffic cells can be transferred to the heavy-traffic cells that need more nominal channels. In this paper, CPSOM is used online for traffic prediction. In this sense, the proposed CPSOM-based BCA method is able to enhance the performance for patterned traffic load compared with the traditional BCA methods. Simulation results corroborate that the proposed method enables the system to work with better performance for patterned traffic load than the traditional BCA methods.     

CPE: a parallel library for financial engineering applications

The Clustertech parallel environment is an object-oriented C++ library that uses abstractions to simplify parallel programming for financial engineering applications. The message passing interface ensures CPE's portability and performance over a wide range of parallel cluster and symmetric multiprocessing machines.     

PRSOM: a new visualization method by hybridizing multidimensional scaling and self-organizing map

Self-organizing map (SOM) is an approach of nonlinear dimension reduction and can be used for visualization. It only preserves topological structures of input data on the projected output space. The interneuron distances of SOM are not preserved from input space into output space such that the visualization of SOM can be degraded. Visualization-induced SOM (ViSOM) has been proposed to overcome this problem. However, ViSOM is derived from heuristic and no cost function is assigned to it. In this paper, a probabilistic regularized SOM (PRSOM) is proposed to give a better visualization effect. It is associated with a cost function and gives a principled rule for weight-updating. The advantages of both multidimensional scaling (MDS) and SOM are incorporated in PRSOM. Like MDS, The interneuron distances of PRSOM in input space resemble those in output space, which are predefined before training. Instead of the hard assignment by ViSOM, the soft assignment by PRSOM can be further utilized to enhance the visualization effect. Experimental results demonstrate the effectiveness of the proposed PRSOM method compared with other dimension reduction methods.     

Pile Behavior due to Excavation-Induced Soil Movement in Clay. I: Stable Wall

A series of centrifuge model tests has been conducted to investigate the behavior of a single pile subjected to excavation-induced soil movements behind a stable retaining wall in clay. The results reveal that after the completion of soil excavation, the wall and the soil continue to move and such movement induces further bending moment and deflection on an adjacent pile. For a pile located within 3?m behind the wall where the soil experiences large shear strain (>2%) due to stress relief as a result of the excavation, the induced pile bending moment and deflection reach their maximum values sometime after soil excavation and thereafter decrease slightly with time. For a pile located 3?m beyond the wall, the induced pile bending moment and deflection continue to increase slightly with time after excavation until the end of the test. A numerical model developed at the National University of Singapore is used to back-analyze the centrifuge test data. The method gives a reasonably good prediction of the induced bending moment and deflection on a pile located at 3?m or beyond the wall. For a pile located at 1?m behind the wall where the soil experiences large shear strain (>2%) due to stress relief resulting from the excavation, the calculated pile response is in good agreement with the measured data if the correct soil shear strength obtained from postexcavation is used in the analysis. However, if the original soil shear strength prior to excavation is used in the analysis, this leads to an overestimation of the maximum bending moment of about 25%. The practical implications of the findings are also discussed in this paper.