Fabrication of buried microfluidic channels with observation windows using femtosecond laser photoablation and parylene-C coating

We developed an advanced method for fabricating microfluidic structures comprising channels and inputs/outputs buried within a silicon wafer based on single level lithography. We etched trenches into a silicon substrate, covered these trenches with parylene-C, and selectively opened their bottoms using femtosecond laser photoablation, forming channels and inputs/outputs by isotropic etching of silicon by xenon difluoride vapors. We subsequently sealed the channels with a second parylene-C layer. Unlike in previously published works, this entire process is conducted at ambient temperature to allow for integration with complementary metal oxide semiconductor devices for smart readout electronics. We also demonstrated a method of chip cryo-cleaving with parylene presence that allows for monitoring of the process development. We also created an observation window for in situ visualization inside the opaque silicon substrate by forming a hole in the parylene layer at the silicon backside and with local silicon removal by xenon difluoride vapor etching. We verified the microfluidic chip performance by forming a segmented flow of a fluorescein solution in an oil stream. This proposed technique provides opportunities for forming simple microfluidic systems with buried channels at ambient temperature.     

Conformance testing in systems with semicontrollable interfaces

In a conformance testing environment, an implementation under test (iut) communicates with multiple entities. A tester may have differing degrees of control on the interactions between these entities and the iut : directly controllable, semicontrollable, or uncontrollable. Semi-controllable inputs most likely render portions of an IUT untestable. In addition, multiple communicating entities may create race conditions during testing. This paper presents a test generation methodology for systems where the semicontrollable inputs can be generated indirectly. The test sequences obtained from the converted graph fully utilize the semicontrollable inputs (where possible) while avoiding the race conditions. Although, for the most general case, the graph conversion results in a exponentially large number of nodes, practical considerations make the converted graph size feasible. This approach is used to generate tests for mil-std 188-220B. By applying the proposed graph conversion and the race condition elimination techniques, the number of testable state transitions increased from approximately 200 to over 700, which represents a coverage of 95% of the transitions defined in the specification.     

A technique to generate feasible tests for communications systems with multiple timers

We present a new model for testing real-time protocols with multiple timers, which captures complex timing dependencies by using simple linear expressions involving timer-related variables. This new modeling technique, combined with the algorithms to eliminate inconsistencies, allows generation of feasible test sequences without compromising their fault coverage. The model is specifically designed for testing to avoid performing full reachability analysis, and to control the growth of the number of test scenarios. Based on extended finite state machines, it is applicable to languages such as SDL, VHDL, and Estelle. The technique models a realistic testing framework in which each I/O exchange takes a certain time to realize and timers can be arbitrarily started or stopped. A software tool implementing this technique is used to generate test cases for the US Army wireless standard MIL-STD 188-220.     

Fault Modeling and Detection Capabilities for EFSM Models

Inherent timing variables and constraints in communication protocols require new extended finite-state machine (EFSM) models to formally represent their behavior, particularly for test generation purposes. However, infeasible paths due to the conflicts among the timing condition and action variables in the timed EFSM models with the activation and expiration of concurrent timers complicate the test generation process. In a test measurement laboratory, such timers, if not properly taken into account by formal methods at the test generation step, can generate false results by failing correct implementations or, worse, passing faulty implementations. This paper analyzes the fault detection capability of the timed EFSM models introduced in our earlier work in the presence of multiple timing faults. It is proven that, for a class of timing faults, test sequences generated from our models can detect multiple occurrences of pairwise combinations of such faults. A simplified version of the session initiation protocol (SIP) registration process, which is widely used by voice over IP (VoIP) telephones, has been used as a working example throughout this paper.     

Lessons learned from automating tests for an operations support system

We present experience gained in automating tests for an operations support system. A major portion of the effort was devoted to extending a commercial test tool so that testers could easily manipulate graphical user interface (GUI) objects on two implementations of the application. For this purpose, we developed a test automation library as support infrastructure for writing tests. The challenges and tradeoffs are discussed such as simplicity/complexity for a tester versus a library developer, hiding/exposing window hierarchy to the tester, providing common methods for different types of GUI objects, transparently manipulating custom GUI widgets, and coping with data‐dependent test cases. We discuss the requirements of test code reusability, maintainability, and portability, and describe the solutions we found. In addition, we offer observations about benefits and pitfalls of test automation, our recommendations for maximizing return on investment, and results from automating a variety of tests. Copyright © 2002 John Wiley & Sons, Ltd.     

Near‐infrared activation of semi‐crystalline shape memory polymer nanocomposites

Recently, indirect activation of the shape memory effect has become an increasingly popular triggering modality for shape memory polymer biomaterials. Amongst the known methods for remote activation, near‐infrared radiation (NIR) remains relatively unexplored, specifically for semicrystalline materials, which possess sharp thermal transitions. Herein, poly(ε‐caprolactone) (PCL) networks were photo‐polymerized from branched precursors doped with 150 nm surface modified gold nanoshells with a surface plasmon resonance of approximately 800 nm. The effect of nanoparticle loading on the thermal, mechanical, and shape memory properties of the PCL matrix were examined. The PCL nanocomposites exhibited excellent shape fixation and nearly quantitative shape memory recovery in response to low intensity NIR irradiation. Further, the heat dissipated by the irradiated nanocomposites to the surrounding medium was found to reach a maximum at biologically relevant temperatures. As such, this nanocomposite system represents a highly attractive candidate for many biomedical shape memory applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4551–4557, 2013     

Evaluation of architectures for reliable server pooling in wired and wireless environments

Reliable server pooling (RSP) allows a pool of redundant information sources to be viewed as a single transport endpoint and, therefore, it is able to provide persistent connections and balanced traffic for different applications. The Internet Engineering Task Force RSerPool Working Group has proposed an architecture to implement the RSP; it defines an overlay network providing an upper layer protocol or an application with a range of reliability services, from simple server selection to a fully automatic session-failover capability. The simulation experiments conducted in both wired and wireless environments show that the current version of the RSerPool works well in fixed and relatively reliable environments, but its performance worsens rapidly as the networks become more unreliable or mobile. The issues we have identified in wireless mobile ad hoc networks include network partition, high signaling overhead, difficulty in synchronization among name servers, and excessive aggressiveness in handling failures. Alternative design options for the RSP in wireless and mobile environments are introduced and evaluated.     

捷克煤炭开采及矿区土地复垦现状分析

采用实地考察、文献查阅、定性与定量分析及比较分析等方法,综合介绍了有着悠久煤炭开采和土地复垦历史的捷克煤炭开采现状,全面分析了捷克煤矿区土地复垦历史、复垦方向、复垦技术及政策法规与资金来源等,并与中国进行了初步比较,揭示了捷克煤矿区土地复垦的4个特点:林地优先且休闲绿地比重增加;土地复垦工作体系相对完善;企业可持续发展信息公开且统计规范;复垦技术相对成熟但同样面临自燃煤矸石山难于治理等问题。研究结果对增进国际交流及探寻中国煤炭行业可持续发展的方向具有积极的意义。