Doctor of Philosophy

dissertationMessage passing (MP) has gained a widespread adoption over the years, so much so, that even heterogeneous embedded multicore systems are running programs that are developed using message passing libraries. Such a phenomenon is a shift in computing practices, since, traditionally MP programs have been developed specifically for high performance computing. With growing importance and the complexity of MP programs in today's times, it becomes absolutely imperative to have formal tools and sound methodologies that can help reason about the correctness of the program. It has been demonstrated by many researchers in the area of concurrent program verification that a suitable strategy to verify programs which rely heavily on nondeterminism, is dynamic verification. Dynamic verification integrates the best features of testing and model checking. In the area of MP program verification, however, there have been only a handful of dynamic verifiers. These dynamic verifiers, despite their strengths, suffer from the explosion in execution scenarios. All existing dynamic verifiers, to our knowledge, exhaustively explore the nondeterministic choices in an MP program. It is apparent that an MP program with many nondeterministic constructs will quickly inundate such tools. This dissertation focuses on the problem of containing the exponential space of execution scenarios (or interleavings) while providing a soundness and completeness guarantee over safety properties of MP programs (specifically deadlocks). We present a predictive verification methodology and an associated framework, called MAAPED(Messaging Application Analysis with Predictive Error Discovery), that operates in polynomial time over MP programs to detect deadlocks among other safety property violations. In brief, we collect a single execution trace of an MP program and without re-running other execution schedules, reliably construct the artifacts necessary to predict any mishappening in an unexplored execution schedule with the aforementioned formal guarantee. The main contributions of the thesis are the following: The Functionally Irrelevant Barrier Algorithm to increase program productivity and ease in verification complexity. A sound pragmatic strategy to reduce the interleaving space of existing dynamic verifiers which is complete only for a certain class of MPI programs. A generalized matches-before ordering for MP programs. A predictive polynomial time verification framework as an alternate solution in the dynamic MP verification landscape. A soundness and completeness proof for the predictive framework's deadlock detection strategy for many formally characterized classes of MP programs. In the process of developing solutions that are mentioned above, we also collected important experiences relating to the development of dynamic verification schedulers. We present those experiences as a minor contribution of this thesis

Unfolding-based Partial Order Reduction

Partial order reduction (POR) and net unfoldings are two alternative methods to tackle state-space explosion caused by concurrency. In this paper, we propose the combination of both approaches in an effort to combine their strengths. We first define, for an abstract execution model, unfolding semantics parameterized over an arbitrary independence relation. Based on it, our main contribution is a novel stateless POR algorithm that explores at most one execution per Mazurkiewicz trace, and in general, can explore exponentially fewer, thus achieving a form of super-optimality. Furthermore, our unfolding-based POR copes with non-terminating executions and incorporates state-caching. Over benchmarks with busy-waits, among others, our experiments show a dramatic reduction in the number of executions when compared to a state-of-the-art DPOR.Comment: Long version of a paper with the same title appeared on the proceedings of CONCUR 201

Rayleigh-Ritz method for analyzing free vibration of orthotropic rectangular plate with 2D thickness and temperature variation

A plate structure is of key interest to aerospace, mechanical and civil engineers. Vibration reduction is a major challenge pertaining to these fields; especially in aerospace applications, such a reduction must be achieved with a minimal increase in weight. The vibration of plates is a special case of the more general problem of mechanical vibrations. In this paper effect of bi-parabolic variation in temperature is premeditated on vibration of an orthotropic rectangular plate and whose thickness also varies bi-linear as in two dimensional. Frequency equation is derived by using Rayleigh-Ritz technique with a two-term deflection function. Time period, Deflection and Logarithmic decrement at different points for the first two modes of vibration are calculated for various values of thermal gradients, aspect ratio and taper constants

A survey of MPI related debuggers and tools

technical reportMessage Passing Interface is a widely used standard in the High Performance and Scienti c Computing Community for writing programs that can exploit the capability of parallel platforms. However, the inherent complexity and the size of the communication standard have made it difficult for programmers to use it efficiently and more importantly correctly. There are numerous tools and debuggers written by various academic/industry communities to nd bugs in the MPI programs written by users. Some of them are MPI-CHECK (Iowa state Univ, [12]), MPIDD (UNBC, Canada [6]), UMPIRE (LLNL, [15]), Intel Message Checker (Intel, [5]), MARMOT (HLRS, [8]) and TotalView ([1]). A brief analysis and comparison of these tools are presented below. In addition, this report presents an overview of the debugging support build into some of the currently popular MPI libraries

Efficient Adversarial Input Generation via Neural Net Patching

The generation of adversarial inputs has become a crucial issue in establishing the robustness and trustworthiness of deep neural nets, especially when they are used in safety-critical application domains such as autonomous vehicles and precision medicine. However, the problem poses multiple practical challenges, including scalability issues owing to large-sized networks, and the generation of adversarial inputs that lack important qualities such as naturalness and output-impartiality. This problem shares its end goal with the task of patching neural nets where small changes in some of the network's weights need to be discovered so that upon applying these changes, the modified net produces the desirable output for a given set of inputs. We exploit this connection by proposing to obtain an adversarial input from a patch, with the underlying observation that the effect of changing the weights can also be brought about by changing the inputs instead. Thus, this paper presents a novel way to generate input perturbations that are adversarial for a given network by using an efficient network patching technique. We note that the proposed method is significantly more effective than the prior state-of-the-art techniques

CLINICAL EFFICACY OF VRAHAT DADIMASHTAK CHOORNA: A CRITICAL REVIEW

According to Ayurvedic literature, the potency and efficacy (Saviryata awadhi) of Ayurvedic classical preparations depend upon quality of each drug (having Rasa panchak), desh (region), Kal (time), Ritu (season), their preparation method and route of administration. But now a day, in modern science got after research these concepts molded and depend on chemical composition of each drug or preparation. Here we describe the claims of Vrahat dadimashtak choorna in various diseases especially in Gastro-intestinal ailments. As per Acharya Sharangdhar, Vrahat dadimashtak choorna is useful for the treatment of following disorders:-Atisaar (diarrhoea) Kshaya (phthisis), Gulma (abdominal tumor/abdominal lump), Grahani (sprue), Galagraha (pain in throat), Mandagni (Improper digestion), Peenus (rhinitis), Kas (cough). The all contents of Vrahat dadimashtak choorna have been evaluated according to the research done by various research scholars. The efficacy has been also tested according to the Rasa, Guna, Virya, Vipaka described in Ayurvedic text. In this research paper we are try to establish the claims of old Ayurvedic text on the recent research parameters

Ultrasonic Standoff Photoacoustic Sensor for the Detection of Explosive and Hazardous Molecules

Standoff photoacoustic spectroscopic technique has been studied for the detection of hazardous molecules adsorbed on surfaces and in vapour/aerosols form in open air. Detection and identification of components in explosive mixtures in trace amounts is very challenging by any point or standoff spectroscopic detection technique. Discusses detection and identification of such components using standoff laser photoacoustic spectroscopic technique. Laser photoacoustic spectra of various trace molecules in the mid-infrared spectral band 7 μm - 9 μm have been recorded in vapor, aerosol, liquid forms as well as samples adsorbed on surfaces such as plastic and cloth. Pulsed quantum cascade laser is modulated at a frequency of 42 kHz resonant with that of microphone. Hazardous chemicals/explosives adsorbed on plastic and cloths surfaces were detected from a standoff distance up to 1.5 m. The sensitivities were found to be 20 μg/cm2, 20 μl liquid and 1.0 ppm corresponding to solid, liquid and vapour phases respectively. The chemicals/explosives used in the study were PETN, DNT, Acetone, and DMMP. Our study suggests that the photoacoustic technique has high selectivity and sensitivity for the trace detection and be used for screening of suspicious objects for security applications as a handy product