Improving the electrical integrity of Cu-CoSi/sub 2/ contacted n/sup +/p junction diodes using nitrogen-incorporated Ta films as a diffusion barrier

The study on improving the electrical integrity of Cu-CoSi/sub 2/ contacted-junction diodes by using the reactively sputtered TaN/sub x/ as a diffusion barrier is presented in this paper. In this study, the Cu (300 nm)-CoSi/sub 2/ (50 nm)/n/sup +/p junction diodes were intact with respect to metallurgical reaction up to a 350/spl deg/C thermal annealing while the electrical characteristics started to degrade after annealing at 300/spl deg/C in N/sub 2/ ambient for 30 min. With the addition of a 50-nm-thick TaN/sub x/ diffusion barrier between Cu and CoSi/sub 2/, the junction diodes were able to sustain annealing up to 600/spl deg/C without losing the basic integrity of the device characteristics, and no metallurgical reaction could be observed even after a 750/spl deg/C annealing in a furnace. In addition, the structure of TaN/sub x/ layers deposited on CoSi/sub 2/ at various nitrogen flow rates has been investigated. The TaN/sub x/ film with small grain sizes deposited at nitrogen flow ratios exceeding 10% shows better barrier capability against Cu diffusion than the others.     

In vitro antimicrobial activity of fluoroquinolones against clinical isolates obtained in 1989 and 1990

The in vitro activity of nine fluoroquinolones, enoxacin, norfloxacin, ofloxacin, ciprofloxacin, lomefloxacin, tosufloxacin, sparfloxacin, fleroxacin and levofloxacin, and two earlier quinolones, nalidixic acid and pipemidic acid, against 1,346 bacterial strains isolated clinically between 1989 and 1990, was evaluated by agar dilution method. The bacteria studied were Staphylococcus aureus (including methicillin-susceptible and -resistant strains), Staphylococcus epidermidis, Enterococcus species (including high-level gentamicin-resistant strains), Escherichia coli, Salmonella species, Proteus mirabilis, Proteus vulgaris, Morganella morganii, Klebsiella pneumoniae, Enterobacter cloacae, Serratia marcescens, Citrobacter spp., Pseudomonas aeruginosa, Pseudomonas cepacia, Acinetobacter baumannii, and Bacteroides fragilis. In contrast to the moderate to poor activity of two earlier quinolones, the fluoroquinolones acted well against most Enterobacteriaceae and A. baumannii. The minimum inhibitory concentrations for 90% of the drug strains (MIC90s) were < 1 microgram/mL against most tested species. Ciprofloxacin, tosufloxacin, sparfloxacin, and levofloxacin were more effective against multi-drug-resistant nosocomial pathogens. All fluoroquinolones assayed were very active against methicillin-susceptible S. aureus, with MIC90s < or = 1 microgram/mL. For methicillin-resistant strains, on the other hand, the MIC90s were > or = 4 micrograms/mL. There was no significant difference in fluoroquinolone susceptibility between methicillin-susceptible and -resistant S. epidermidis. Sparfloxacin, tosufloxacin, ciprofloxacin and levofloxacin were more active against enterococci. Most fluoroquinolones were relatively inactive against B. fragilis, with the exception of tosufloxacin, sparfloxacin and levofloxacin. The MIC90s of most quinolones assayed against K. pneumoniae, Citrobacter spp., E. cloacae, S. aureus and S. epidermidis were at least four-fold higher in our study. Therefore, it is important for physicians to use fluoroquinolones carefully so as to prevent or delay the emergence of resistant strains.     

Large-scale convex optimal control problems: time decomposition,incentive coordination, and parallel algorithm

A parallel algorithm based on time decomposition and incentive coordination is developed for long-horizon optimal control problems. This is done by first decomposing the original problem into subproblems with shorter time horizon, and then using the incentive coordination scheme to coordinate the interaction of subproblems. For strictly convex problems it is proved that the decomposed problem with linear incentive coordination is equivalent to the original problem, in the sense that each optimal solution of the decomposed problem produces one global optimal solution of the original problem and vice versa. In other words, linear incentive terms are sufficient in this case and impose no additional computation burden on the subproblems. The high-level parameter optimization problem is shown to be nonconvex, despite the uniqueness of the optimal solution and the convexity of the original problem. Nevertheless, the high-level problem has no local minimum, even though it is nonconvex. A parallel algorithm based on a prediction method is developed, and a numerical example is used to demonstrate the feasibility of the approach     

Security and Privacy for Distributed Multimedia Sensor Networks

There is a critical need to provide privacy and security assurances for distributed multimedia sensor networking in applications including military surveillance and healthcare monitoring. Such guarantees enable the widespread adoption of such information systems, leading to large-scale societal benefit. To effectively address protection and reliability issues, secure communications and processing must be considered from system inception. Due to the emerging nature of broadband sensor systems, this provides fertile research ground for proposing more paradigm-shifting approaches. This paper discusses issues in designing for security and privacy in distributed multimedia sensor networks. We introduce the heterogeneous lightweight sensornets for trusted visual computing framework for distributed multimedia sensor networks. Protection issues within this architecture are analyzed, leading to the development of open research problems including secure routing in emerging free-space optical sensor networks and distributed privacy for vision-rich sensor networking. Proposed solutions to these problems are presented, demonstrating the necessary interaction among signal processing, networking, and cryptography.     

Three-level Stackelberg decision problems

Three-level Stackelberg decision problems are studied by using the inducible region concept. Through a systematic derivation, it is identified that the leader's control has dual purposes, which in general are not separable. A special class of problems is then considered, where explicit results are obtained.     

A rational surgical approach for intra-thoracic esophageal perforation

The surgical experiences of intrathoracic esophageal perforation in 17 consecutive cases seen during the last eight years are reviewed. Using a rational approach to this critical condition, the mortality and morbidity rates were lower than before. For acute perforation in a corrosive-injured esophagus, subtotal esophagectomy by eversion stripping was an effective procedure for life saving. For acute perforation of a normal or chronic fibrotic but functional esophagus, early primary repair was usually successful for healing. For chronic esophageal perforation, usually complicated by mediastinal abscess or purulent pleural effusion, an adequate local drainage or supplemented with a newly designed, temporary diversion procedure for drainage of saliva and gastric acid was recommended.     

An optimization-based algorithm for job shop scheduling

Scheduling is a key factor for manufacturing productivity. Effective scheduling can improve on-time delivery, reduce inventory, cut lead times, and improve the utilization of bottleneck resources. Because of the combinatorial nature of scheduling problems, it is often difficult to find optimal schedules, especially within a limited amount of computation time. Production schedules therefore are usually generated by using heuristics in practice. However, it is very difficult to evaluate the quality of these schedules, and the consistency of performance may also be an issue. In this paper, near-optimal solution methodologies for job shop scheduling are examined. The problem is formulated as integer optimization with a “separable” structure. The requirement of on-time delivery and low work-in-process inventory is modelled as a goal to minimize a weighted part tardiness and earliness penalty function. Lagrangian relaxation is used to decompose the problem into individual part subproblems with intuitive appeal. By iteratively solving these subproblems and updating the Lagrangian multipliers at the high level, near-optimal schedules are obtained with a lower bound provided as a byproduct. This paper reviews a few selected methods for solving subproblems and for updating multipliers. Based on the insights obtained, a new algorithm is presented that combines backward dynamic programming for solving low level subproblems and interleaved conjugate gradient method for solving the high level problem. The new method significantly improves algorithm convergence and solution quality. Numerical testing shows that the method is practical for job shop scheduling in industries. This work was supported in part by the National Science Foundation under DMI-9500037, and the Advanced Technology Center for Precision Manufacturing, University of Connecticut.     

Incentives in production: a case study

The motivation, rationale, and experiences of implementing an incentive scheme in a large petrochemical plant in the People's Republic of China for the purpose of conserving the consumption of cooling water is described. Experimental implementation in a section of a plant is described in detail. A few incentive-induced features uncovered after analyzing the experimental data are reported. A mathematical model with several variations is presented. A better predictive property of the incentive scheme in comparison to a more conventional method is proved analytically. The effectiveness of the scheme is shown by the amount of water conserved, and by the management's decision for plantwide adoption of the scheme. Practical issues encountered in experimental implementation, extensions of the scheme to more general situations, and theoretical problem inspired by the experiment are discussed     

Clinical features of tuberculosis associated with HIV infection in Taiwan

To understand the clinical characteristics and outcome of tuberculosis (TB) in patients with acquired immunodeficiency syndrome (AIDS) in Taiwan, we reviewed the medical records of 118 adult AIDS patients who were hospitalized at National Taiwan University Hospital between January 1988 and September 1995. Among them, 29 (24.6%) had TB. The mean age of the AIDS patients with TB was 37 years (range, 25-66 yr). Most patients were in the advanced stages of AIDS when human immunodeficiency virus (HIV) infection and/or TB were first diagnosed. The mean CD4+ lymphocyte count was 0.037 x 10(9)/L (range, 0-0.152 x 10(9)/L) at the time TB was diagnosed. There was no statistically significant difference in the mean CD4+ lymphocyte count between patients with isolated pulmonary TB and those with extrapulmonary involvement. Twenty-two patients (75.8%) had extrapulmonary TB with the most common site being the lymph nodes (72.7%). Clinical symptoms were nonspecific, and the chest physical examination was not helpful in the diagnosis. Acid-fast bacilli were detected in sputum smears from eight patients (36.4%). A primary tuberculosis pattern (hilar adenopathy, pleural effusion, middle or lower lobe infiltrates) in the chest radiographs was the most common radiologic finding (36.4%) in patients with pulmonary TB. The reactivation pattern (predominant upper-lobe infiltrates with or without cavitation) could only be found in cases of pulmonary TB without extrapulmonary involvement. Atypical patterns (diffuse interstitial infiltrates mimicking Pneumocystis carinii pneumonia or other patterns) and normal chest radiographs were noted in nearly one-third of the patients with pulmonary TB. A good response to antituberculosis drugs and a favorable outcome were demonstrated in the patients, except for two with drug-resistant Mycobacterium tuberculosis infection. Early identification of TB in HIV-infected patients requires clinical awareness of the unusual clinical presentations, especially among patients in the advanced stages of AIDS.     

Redundancy and coordination of multiple robots

The robots in automation may be used to serve their surrounding equipment such as transporting, loading, and unloading simple objects. For some tasks, two or more robots working together may be required to achieve the assigned goals. In this situation, coordination of the robots for a concerted action becomes a necessity. In addition, the joint torque distribution among the robots is desirable to avoid overloading.