Plastic instability in dual-pressure tube-hydroforming process

The tube-hydroforming process has become an indispensable manufacturing technique in recent years. Successful tube hydroforming requires bulging to take place without causing any type of instability such as bursting, wrinkling or buckling. The dual-pressure tube-hydroforming process was introduced to achieve a favorable tri-axial stress state in the deformation process. In this paper, the effect of applying counter pressure on plastic instability of thin-walled tubes is analyzed. It is concluded that in dual-pressure tube hydroforming, the onset of plastic instability is delayed and the ductility of the metal is increased.     

Verification of evolving software via component substitutability analysis

This paper presents an automated and compositional procedure to solve the substitutability problem in the context of evolving software systems. Our solution contributes two techniques for checking correctness of software upgrades: (1) a technique based on simultaneous use of over-and under-approximations obtained via existential and universal abstractions; (2) a dynamic assume-guarantee reasoning algorithm—previously generated component assumptions are reused and altered on-the-fly to prove or disprove the global safety properties on the updated system. When upgrades are found to be non-substitutable, our solution generates constructive feedback to developers showing how to improve the components. The substitutability approach has been implemented and validated in the ComFoRT reasoning framework, and we report encouraging results on an industrial benchmark. This is an extended version of a paper, Dynamic Component Substitutability Analysis, published in the Proceedings of the Formal Methods 2005 Conference, Lecture Notes in Computer Science, vol. 3582, by the same authors. This research was sponsored by the National Science Foundation under grant nos. CNS-0411152, CCF-0429120, CCR-0121547, and CCR-0098072, the Semiconductor Research Corporation under grant no. TJ-1366, the US Army Research Office under grant no. DAAD19-01-1-0485, the Office of Naval Research under grant no. N00014-01-1-0796, the ICAST project and the Predictable Assembly from Certifiable Components (PACC) initiative at the Software Engineering Institute, Carnegie Mellon University. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of any sponsoring institution, the US government or any other entity.     

Green synthesis of highly stable carbon nanodots and their photocatalytic performance

The present study reports a novel, facile, biosynthesis route for the synthesis of carbon nanodots (CDs) with an approximate quantum yield of 38.5%, using Musk melon extract as a naturally derived‐precursor material. The synthesis of CDs was established by using ultraviolet–visible (UV–vis) spectroscopy, Dynamic light scattering, photoluminescence spectroscopy, X‐ray diffraction, transmission electron microscopy and Fourier transform infrared (FTIR) spectroscopy. The as‐prepared CDs possess an eminent fluorescence under UV–light (λ _ex  = 365 nm). The size range of CDs was found to be in the range of 5–10 nm. The authors further explored the use of such biosynthesised CDs as a photocatalyst material for removal of industrial dye. Degradation of methylene blue dye was performed in a photocatalytic reactor and monitored using UV–vis spectroscopy. The CDs show excellent dye degradation capability of 37.08% in 60 min and reaction rate of 0.0032 min⁻¹. This study shows that synthesised CDs are highly stable in nature, and possess potential application in wastewater treatment.Inspec keywords: carbon, nanostructured materials, nanofabrication, catalysis, photochemistry, ultraviolet spectra, visible spectra, photoluminescence, X‐ray diffraction, transmission electron microscopy, Fourier transform infrared spectra, fluorescence, dyesOther keywords: green synthesis, highly stable CD, photocatalytic performance, biosynthesis route, carbon nanodots, quantum yield, Musk melon extract, naturally derived‐precursor material, ultraviolet‐visible spectroscopy, dynamic light scattering, photoluminescence spectroscopy, X‐ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, FTIR spectroscopy, fluorescence, biosynthesised CD, photocatalyst material, industrial dye, methylene blue dye degradation, photocatalytic reactor, UV‐vis spectroscopy, wastewater treatment, size 5 nm to 10 nm, time 60 min     

A password based authentication scheme for wireless multimedia systems

In this digital era, where Internet of Things (IoT) is increasing day by day, use of resource constrained devices is also increasing. Indeed, the features such as low cost, less maintenance, more adaptive to hostile environment, etc. make the wireless multimedia devices to be the best choice as the resource constrained devices. For the security, the end user device requires to establish the session key with the server before transferring the data. Mobile is one of the device having more and more usage as wireless multimedia device in recent years. In 2013, Li et al. proposed an efficient scheme for the wireless mobile communications and claimed it to be secure against various attacks. Recently, Shen et al. claimed that the scheme of Li et al. is still vulnerable to the privileged insider attack, the stolen verifier attack and finally proposed a scheme to withstand the mentioned and other attacks. However, in this paper we claim that the scheme of Shen et al. is still susceptible to the user anonymity, the session specific temporary information attack and the replay attack. In addition, Shen et al.’s scheme requires more time due to many operations. Further, we propose an efficient scheme that is secure against various known attacks and due to reduced time complexity our scheme is a preferred choice for the wireless mobile networks and hence for wireless multimedia systems.     

Optimum lateral extent of soil domain for dynamic SSI analysis of RC framed buildings on pile foundations

This article describes a novel approach for deciding optimal horizontal extent of soil domain to be used for finite element based numerical dynamic soil structure interaction (SSI) studies. SSI model for a 12 storied building frame, supported on pile foundation-soil system, is developed in the finite element based software framework, OpenSEES. Three different structure-foundation configurations are analyzed under different ground motion characteristics. Lateral extent of soil domain, along with the soil properties, were varied exhaustively for a particular structural configuration. Based on the reduction in the variation of acceleration response at different locations in the SSI system (quantified by normalized root mean square error, NRMSE), the optimum lateral extent of the soil domain is prescribed for various structural widths, soil types and peak ground acceleration levels of ground motion. Compared to the past studies, error estimation analysis shows that the relationships prescribed in the present study are credible and more inclusive of the various factors that influence SSI. These relationships can be readily applied for deciding upon the lateral extent of the soil domain for conducting precise SSI analysis with reduced computational time.     

Towards Supramolecular Catalysis with Small Self-assembled Peptides

Self-assembly of small peptides offers unique opportunities for the bottom-up construction of supramolecular catalysts that aim to emulate the efficiency and selectivity of natural enzymes. Small, information-rich, simple molecules based on amino acids can self-organise autonomously into complex systems with emergent catalytic properties. The power of noncovalent interactions can be used to construct supramolecular peptidic tertiary structures. Moreover, specific functional groups present in amino acid side-chains may present either a catalytic activity by themselves or be able to bind cofactors such as metal ions. In this scenario, although relevant progress has been achieved in recent years, promising applications in biomaterials science are foreseen. In this review, we discuss the state-of-the-art of this approach at the interface between supramolecular chemistry and peptide science.     

Effect of High Pressure Pretreatments on Structural and Dehydration Characteristics of Aloe Vera (Aloe barbadensis Miller) Cubes

The effect of high-pressure (HP) pretreatments (300–500 MPa for 5–15 min) on dehydration characteristics of aloe vera cubes (AVC), dried at 50–70°C and air velocity of 1–2 m/s, was studied. Pretreatments resulted in higher drying rates, leading to a reduction in drying time compared to untreated ones. The drying rate and drying time were most significantly affected (p < 0.05) by the drying temperature, followed by air velocity, pressure level, and dwell time. HPP enhanced the firmness of AVC with a maximum of up to 21% for the sample treated at 500 MPa for 15 min. Microstructural analysis using scanning electron microscopy (SEM) indicated non-uniform structures in the pretreated and dried AVC samples. Semi-quantitative elemental detection (EDS) confirmed the presence of a considerable amount (14%) of calcium in aloe vera.     

Concurrent software verification with states, events, and deadlocks

We present a framework for model checking concurrent software systems which incorporates both states and events. Contrary to other state/event approaches, our work also integrates two powerful verification techniques, counterexample-guided abstraction refinement and compositional reasoning. Our specification language is a state/event extension of linear temporal logic, and allows us to express many properties of software in a concise and intuitive manner. We show how standard automata-theoretic LTL model checking algorithms can be ported to our framework at no extra cost, enabling us to directly benefit from the large body of research on efficient LTL verification. We also present an algorithm to detect deadlocks in concurrent message-passing programs. Deadlock- freedom is not only an important and desirable property in its own right, but is also a prerequisite for the soundness of our model checking algorithm. Even though deadlock is inherently non-compositional and is not preserved by classical abstractions, our iterative algorithm employs both (non-standard) abstractions and compositional reasoning to alleviate the state-space explosion problem. The resulting framework differs in key respects from other instances of the counterexample-guided abstraction refinement paradigm found in the literature. We have implemented this work in the magic verification tool for concurrent C programs and performed tests on a broad set of benchmarks. Our experiments show that this new approach not only eases the writing of specifications, but also yields important gains both in space and in time during verification. In certain cases, we even encountered specifications that could not be verified using traditional pure event-based or state-based approaches, but became tractable within our state/event framework. We also recorded substantial reductions in time and memory consumption when performing deadlock-freedom checks with our new abstractions. Finally, we report two bugs (including a deadlock) in the source code of Micro-C/OS versions 2.0 and 2.7, which we discovered during our experiments. This research was sponsored by the National Science Foundation (NSF) under grants no. CCR-9803774 and CCR-0121547, the Office of Naval Research (ONR) and the Naval Research Laboratory (NRL) under contract no. N00014-01-1-0796, the Army Research Office (ARO) under contract no. DAAD19-01-1-0485, and was conducted as part of the Predictable Assembly from Certifiable Components (PACC) project at the Software Engineering Institute (SEI). This article combines and builds upon the papers (CCO⁺04) and (CCOS04). Received December 2004 Revised July 2005 Accepted July 2005 by Eerke A. Boiten, John Derrick, Graeme Smith and Ian Hayes     

Application of response surface methodology to optimize diesel engine parameters fuelled with pongamia biodiesel/diesel blends

ABSTRACT

In the present scenario, the rate of fossil fuel consumption is very high and increasing rapidly which lead to a further increase in air pollution levels. Due to an increase in pollution level, researchers are striving to discover some cleaner and environment-friendly fuels for the diesel engines. This study was focused on the optimization of the input parameters of the diesel engine running on pongamia biodiesel for improvement in the engine performance. The input parameters selected for optimization were fuel injection pressure, fuel injection timing, pongamia biodiesel blends, and engine load with respect to BTE, BSFC, exhaust gas temperature, and P_max. An experimental analysis was performed according to the response surface methodology technique. The best engine input parameters setting for getting optimum performance was found at fuel injection timing 25 bTDC, fuel injection pressure 226 bar, 40% of pongamia biodiesel blending, at 74% of maximum rated engine load. Experimental and optimized results of the output responses at optimum input parameters were compared and found in the suggested error range.     

Molecularly Targeted Agents as Radiosensitizers in Cancer Therapy—Focus on Prostate Cancer

As our understanding of the molecular pathways driving tumorigenesis improves and more druggable targets are identified, we have witnessed a concomitant increase in the development and production of novel molecularly targeted agents. Radiotherapy is commonly used in the treatment of various malignancies with a prominent role in the care of prostate cancer patients, and efforts to improve the therapeutic ratio of radiation by technologic and pharmacologic means have led to important advances in cancer care. One promising approach is to combine molecularly targeted systemic agents with radiotherapy to improve tumor response rates and likelihood of durable control. This review first explores the limitations of preclinical studies as well as barriers to successful implementation of clinical trials with radiosensitizers. Special considerations related to and recommendations for the design of preclinical studies and clinical trials involving molecularly targeted agents combined with radiotherapy are provided. We then apply these concepts by reviewing a representative set of targeted therapies that show promise as radiosensitizers in the treatment of prostate cancer.