Creation of arbitrary spectra with an acousto-optic modulator and an injection-locked diode laser

We use a double-passed acousto-optic modulator (AOM), driven by an arbitrary waveform generator to produce multiple frequency components for a laser with arbitrary frequency spacings. A programmed sequence containing various sections of radio-frequency sinusoidal signal at different frequency is applied to drive the AOM. The diffracted light is used to injection-lock a diode laser. The combined techniques allow us to generate the multi-line spectra for the diode laser with arbitrary frequency spacings in the range of 100 MHz at a relatively high output power of 80 mW and a small power variation of 2%. Such a light source can be used in the application for laser cooling of molecules.     

Fabrication of Dicing-Free Vertical-Structured High-Power GaN-Based Light-Emitting Diodes With Selective Nickel Electroplating and Patterned Laser Liftoff Techniques

Through the use of selective nickel (Ni) electroplating, patterned laser liftoff technique, and surface roughing of the top n-GaN epilayer, a novel process for the fabrication of vertical-structured metal-substrate GaN-based light-emitting diodes (VM-LEDs) to avoid difficulties in Ni substrate dicing and improve device yield was proposed and demonstrated. In conjunction with a sidewall passivation with SiO₂ and keeping the size of epilayer smaller than that of Ni island, a considerable improvement in yield and device performance were shown. As compared to conventional lateral-structured GaN-based LEDs, VM-LEDs show an increase in light output power about 174% at 350 mA with a significant decrease in forward voltage from 3.5 to 3.17 V     

The characteristics of a dual-layer optical disk with read-only anderasable functions

A dual-layer optical disk comprised of a read only layer and a phase-change layer was designed to perform the read-only and erasable dual-functionality in an optical disk. With the properly designed dual-layer disk structure, 23 mW of write power was adequate to write data marks on the erasable phase-change layer; simultaneously, equal magnitude of sufficient radiofrequency readout signals could be obtained on both its data layers. The analyzes of its recording characteristics demonstrated the feasibility of the dual-functional optical disk     

Effects of using a portable navigation system and paper map in real driving

Navigation systems are very useful tools because they display a user's location and guide them to a destination using graphics, text and voice information. Recent work has revealed that millions of consumers received driving directions using their cell phone or PDA. This present work aimed to explore whether the efficiency to destination and driver behavior were distinguishable when using a portable navigation system compared to a paper map. Thirty-two subjects were paid to participate in this research, with field experiments being carried out in both urban and rural environments. A smart phone was adopted as the portable navigation system in the study. The results revealed that the drivers performed better when using a portable navigation system compared to those using a paper map, in terms of efficiency to destination and driving performance. In addition, drivers could save time and gasoline using a portable navigation system when in an unfamiliar region, and driving performance may be safer, despite the fact that the display screen of the phone is small.     

Using case-based reasoning to establish a continuing care information system of discharge planning

As family structure changes, population is aging and disease styles tend to be chronic, long-term care in Taiwan becomes problematic, needs to be addressed, and requires immediate solution. Presently, many medical care institutions in the country have assisted patients in discharge planning; however, the lack of a standard evaluation procedure in the process of discharge planning is disturbing for each hospital. Without it, there might be huge differences in the evaluation results. Moreover, the lack of support and the uncertainty of case eligibility standard in these institutions further affect the performance of continuing care services.

This research adopted Case-Based Reasoning to establish a continuing care information system of discharge planning. With previously evaluated information of past cases, the similarity index is compared among new cases. In coordinate with Analytic Hierarchy Process, index weight is calculated to reason an old case that is most closely related to the condition of the new case. This information system can assist discharge-planning staff in accurately formulating a plan of action based on previous case-assessment experience and in obtaining valuable information that helps make decision. Through the implementation of the system, accumulation on knowledge and experience of continuing care models will help staff evaluate process of discharge planning to achieve a reasonable, standardized, and simplified procedure as a whole.

This research will transform the evaluating experience of discharge-planning professionals into an assessment method with the application of computer reasoning to make the evaluation process of discharge planning convenient as well as to save more time for discharge-planning professionals to further understand the actual conditions of each case. On the other hand, this information system will provide discharge-planning staff with a set of recommendations as references for making individual discharge plan. It is expected through this research that each hospital be provided with a blue print of improvement in case evaluation process and management.     

Implementing an optimal policy for set-up time reduction in an economic production quantity model

An economic production quantity (EPQ) system consisting of single and multiple items with an optimal policy of set-up time reduction and a fixed increment cost are discussed in the present study. The set-up time reduction ratio as a decision variable under various cases of demand in the EPQ model is considered. It is assumed that the set-up cost is linearly related to the set-up time. The set-up time reduction ratio and the lot size are solved simultaneously to obtain an optimal value of the total annual cost. Numerical examples are presented to demonstrate the accuracy of the proposed method.     

Prediction model building with clustering-launched classification and support vector machines in credit scoring

Recently, credit scoring has become a very important task as credit cards are now widely used by customers. A method that can accurately predict credit scoring is greatly needed and good prediction techniques can help to predict credit more accurately. One powerful classifier, the support vector machine (SVM), was successfully applied to a wide range of domains. In recent years, researchers have applied the SVM-based in the prediction of credit scoring, and the results have been shown it to be effective. In this study, two real world credit datasets in the University of California Irvine Machine Learning Repository were selected. SVM and a new classifier, clustering-launched classification (CLC), were employed to predict the accuracy of credit scoring. The advantages of using CLC are that it can classify data efficiently and only need one parameter needs to be decided. In substance, the results show that CLC is better than SVM. Therefore, CLC is an effective tool to predict credit scoring.     

Thermal conduction in Cr3C2/SiC composite

Thermal conduction behaviour of Cr₃C₂/SiC composite is investigated in terms of temperature and SiC content. Experimental results showed that thermal diffusivity of the composite increases with SiC content up to 20 vol%, corresponding to a conductivity maximum, then decreases with further increase of SiC. The reduction in diffusivity and conductivity at higher SiC content may due to formation of small amounts of solid solution at the interface and/or of interfacial gaps due to lack of perfect contact among SiC aggregates leading to increased phonon scattering. The thermal conductivity demonstrates a positive temperature dependence but becomes temperature-independent when SiC content is above 30 vol%. A correlation with composite theory is present.     

Investigation of Au/Ti/Al ohmic contact to N-type 4H–SiC

In this study, investigation on Au/Ti/Al ohmic contact to n-type 4H–SiC and its thermal stability are reported. Specific contact resistances (SCRs) in the range of 10⁻⁴–10⁻⁶ Ω cm², and the best SCR as low as 2.8 × 10⁻⁶ Ω cm² has been generally achieved after rapid thermal annealing in Ar for 5 min at 800 °C and above. About 1–2 order(s) of magnitude improvement in SCR as compared to those Al/Ti series ohmic systems in n-SiC reported in literature is obtained. XRD analysis shows that the low resistance contact would be attributed to the formation of titanium silicides (TiSi₂ and TiSi) and Ti₃SiC₂ at the metal/n-SiC interface after thermal annealing. The Au/Ti/Al ohmic contact is thermally stable during thermal aging treatment in Ar at temperature in the 100–500 °C range for 20 h.     

Operational flexibility and optimal total production cost in multipleitem economic production quantity models

This study investigates the problems of operational flexibility, optimal production rate and production runs in multiple-item economic production quantity models under a rotation cycle basis. The production rate of each item and the system rotation cycle are crucial decision variables in this study. The unit production cost of each item is a function of its production rate. The relationship between the optimal total production cost and operational flexibility, which is affected by the unit production cost function of each item, is analysed. Sensitivity analyses have been conducted to evaluate the effects of operational flexibility on the individual parameters of the unit production cost function. An industrial case has also been presented as an illustration.