Decomposition Kinetics and Cook-Off Numerical Simulation of Insensitive Energetic Plasticizer Plasticized Propellants

Aiming at the thermal safety issues between the insensitive energetic plasticizer and propellant components, NG/BTTN and insensitive energetic plasticizer BuNENA plasticized propellant was compared by DSC test and cook-off numerical simulation, with the thermal safety property evaluated. The decomposition activation energy Ea and self-ignition temperature Tb of BuNENA plasticized propellant was lower than that of NG/BTTN plasticized propellant. Two kinds of propellant responded in the central area during slow cook-off simulation while in the near shell area during medium cook-off simulation. During fast cook-off simulation, depending on the different thickness of insulator, propellant responded at the area near shell or the area near the caps. The response temperature of two propellants in cook-off simulation agreed with decomposition and self-ignition temperature by DSC, and the decomposition of plasticizer could trigger the response. In cook-off simulation, BuNENA plasticized propellant showed a lower response temperature with a smaller high temperature area before response, resulting a milder response and better thermal safety than NG/BTTN plasticized propellant.

Simulation of Fibre Bragg Grating as Strain Sensor for Property Intrusion

This study will demonstrate a strain sensor based on the optical Fibre Bragg Grating (FBG) sensing technology as it is known to have stable and reliable wavelength and response as function of the applied strain. This kind of sensor can perform accurate measurements of small ground vibration and monitor seismic activity thanks to their high sensitivity to dynamic strains induced by acceleration variation which can use to prevent property intrusion or burglary. To understand the FBG sensor more, few of its characteristics such as strain, spectral reflectivity and bandwidth and their connection with the fibre grating length and refractive index is being studied. Keywords: Fibre Bragg Grating(FBG); strain sensor; strain; spectral reflectivity; bandwidth; fibre grating length; refractive index; safety; property intrusion.

Actinomycin X2, an Antimicrobial Depsipeptide from Marine-Derived Streptomyces cyaneofuscatus Applied as a Good Natural Dye for Silk Fabric

Actinomycins as clinical medicine have been extensively studied, while few investigations were conducted to discover the feasibility of actinomycins as antimicrobial natural dye contributing to the medical value of the functional fabrics. This study was focused on the application of actinomycin X2 (Ac.X2), a peptide pigment cultured from marine-derived Streptomyces cyaneofuscatus, in the dyeing and finishing of silk fabric. The dyeing potential of Ac.X2 with silk vs. cotton fabrics was assessed. As a result, the silk fabric exhibited greater uptake and color fastness with Ac.X2. Through Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses, some changes of chemical property for the dyed fabric and Ac.X2 were studied. The silk fabric dyed with Ac.X2 exhibited good UV protection ability. The antibacterial properties of dyed and finished silk were also evaluated, which exhibited over 90% antibacterial activity even after 20 washing cycles. In addition, the brine shrimp assay was conducted to evaluate the general toxicity of the tested fabric, and the results indicated that the dyed silk fabrics had a good biological safety property.

On the Use of Model Checking for the Bounded and Unbounded Verification of Nonblocking Concurrent Data Structures

<p>Concurrent data structure algorithms have traditionally been designed using locks to regulate the behaviour of interacting threads, thus restricting access to parts of the shared memory to only one thread at a time. Since locks can lead to issues of performance and scalability, there has been interest in designing so-called nonblocking algorithms that do not use locks. However, designing and reasoning about concurrent systems is difficult, and is even more so for nonblocking systems, as evidenced by the number of incorrect algorithms in the literature. This thesis explores how the technique of model checking can aid the testing and verification of nonblocking data structure algorithms. Model checking is an automated verification method for finite state systems, and is able to produce counterexamples when verification fails. For verification, concurrent data structures are considered to be infinite state systems, as there is no bound on the number of interacting threads, the number of elements in the data structure, nor the number of possible distinct data values. Thus, in order to analyse concurrent data structures with model checking, we must either place finite bounds upon them, or employ an abstraction technique that will construct a finite system with the same properties. First, we discuss how nonblocking data structures can be best represented for model checking, and how to specify the properties we are interested in verifying. These properties are the safety property linearisability, and the progress properties wait-freedom, lock-freedom and obstructionfreedom. Second, we investigate using model checking for exhaustive testing, by verifying bounded (and hence finite state) instances of nonblocking data structures, parameterised by the number of threads, the number of distinct data values, and the size of storage memory (e.g. array length, or maximum number of linked list nodes). It is widely held, based on anecdotal evidence, that most bugs occur in small instances. We investigate the smallest bounds needed to falsify a number of incorrect algorithms, which supports this hypothesis. We also investigate verifying a number of correct algorithms for a range of bounds. If an algorithm can be verified for bounds significantly higher than the minimum bounds needed for falsification, then we argue it provides a high degree of confidence in the general correctness of the algorithm. However, with the available hardware we were not able to verify any of the algorithms to high enough bounds to claim such confidence. Third, we investigate using model checking to verify nonblocking data structures by employing the technique of canonical abstraction to construct finite state representations of the unbounded algorithms. Canonical abstraction represents abstract states as 3-valued logical structures, and allows the initial coarse abstraction to be refined as necessary by adding derived predicates. We introduce several novel derived predicates and show how these allow linearisability to be verified for linked list based nonblocking stack and queue algorithms. This is achieved within the standard canonical abstraction framework, in contrast to recent approaches that have added extra abstraction techniques on top to achieve the same goal. The finite state systems we construct using canonical abstraction are still relatively large, being exponential in the number of distinct abstract thread objects. We present an alternative application of canonical abstraction, which more coarsely collapses all threads in a state to be represented by a single abstract thread object. In addition, we define further novel derived predicates, and show that these allow linearisability to be verified for the same stack and queue algorithms far more efficiently.</p>

On the Use of Model Checking for the Bounded and Unbounded Verification of Nonblocking Concurrent Data Structures

<p>Concurrent data structure algorithms have traditionally been designed using locks to regulate the behaviour of interacting threads, thus restricting access to parts of the shared memory to only one thread at a time. Since locks can lead to issues of performance and scalability, there has been interest in designing so-called nonblocking algorithms that do not use locks. However, designing and reasoning about concurrent systems is difficult, and is even more so for nonblocking systems, as evidenced by the number of incorrect algorithms in the literature. This thesis explores how the technique of model checking can aid the testing and verification of nonblocking data structure algorithms. Model checking is an automated verification method for finite state systems, and is able to produce counterexamples when verification fails. For verification, concurrent data structures are considered to be infinite state systems, as there is no bound on the number of interacting threads, the number of elements in the data structure, nor the number of possible distinct data values. Thus, in order to analyse concurrent data structures with model checking, we must either place finite bounds upon them, or employ an abstraction technique that will construct a finite system with the same properties. First, we discuss how nonblocking data structures can be best represented for model checking, and how to specify the properties we are interested in verifying. These properties are the safety property linearisability, and the progress properties wait-freedom, lock-freedom and obstructionfreedom. Second, we investigate using model checking for exhaustive testing, by verifying bounded (and hence finite state) instances of nonblocking data structures, parameterised by the number of threads, the number of distinct data values, and the size of storage memory (e.g. array length, or maximum number of linked list nodes). It is widely held, based on anecdotal evidence, that most bugs occur in small instances. We investigate the smallest bounds needed to falsify a number of incorrect algorithms, which supports this hypothesis. We also investigate verifying a number of correct algorithms for a range of bounds. If an algorithm can be verified for bounds significantly higher than the minimum bounds needed for falsification, then we argue it provides a high degree of confidence in the general correctness of the algorithm. However, with the available hardware we were not able to verify any of the algorithms to high enough bounds to claim such confidence. Third, we investigate using model checking to verify nonblocking data structures by employing the technique of canonical abstraction to construct finite state representations of the unbounded algorithms. Canonical abstraction represents abstract states as 3-valued logical structures, and allows the initial coarse abstraction to be refined as necessary by adding derived predicates. We introduce several novel derived predicates and show how these allow linearisability to be verified for linked list based nonblocking stack and queue algorithms. This is achieved within the standard canonical abstraction framework, in contrast to recent approaches that have added extra abstraction techniques on top to achieve the same goal. The finite state systems we construct using canonical abstraction are still relatively large, being exponential in the number of distinct abstract thread objects. We present an alternative application of canonical abstraction, which more coarsely collapses all threads in a state to be represented by a single abstract thread object. In addition, we define further novel derived predicates, and show that these allow linearisability to be verified for the same stack and queue algorithms far more efficiently.</p>

The evaluation of safety property and apoptotic efficacy of α-L-Guluronic Acid (G2013), as a novel NSAID, under in vitro examination on L929 and hepatocellular carcinoma cell lines

Background: Many investigations have expanded this concept that liver chronic inflammation has an essential role in persistent cell damages along with altering the liver microenvironment leading to fibrosis, cirrhosis, and finally, hepatocellular carcinoma (HCC). To reduce inflammation and relieve symptoms, non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used; however, their long-term usage can lead to severe adverse events on vital organs like the liver. Interestingly, the α-L-Guluronic Acid (G2013), as a novel NSAID with immunomodulatory properties, has shown the inhibitory effects on inflammation and metastasis in experimental models. Objective: This study was conducted to determine the effects of G2013 on cytotoxicity and induction of apoptosis, as a new therapeutic target for cancer therapy, in the HepG2 cell line and the mouse fibroblast cell line L929, as a control. Methods: MTT assay and flow cytometry method were carried out using the different concentrations of G2013 (5, 15, 25, 50, 100, 200 and 400 μg/ml) in 3 distinct incubation times. Results: Our data showed that treatment of HepG2 cells with high concentration (400µg/mL) of G2013 could effectively cause a decrease in cell viability, so that they were statistically different after 72 hours compared to other concentrations (5 to 200 μg/ml) (P<0.05 and P<0.01, respectively). Moreover, the proportion of apoptosis of HepG2 cells at the dose of 200µg/mL considerably increased, suggesting that the induction of apoptosis by G2013 in HepG2 cells is dose- and time-dependent, which could promote its anticancer properties. Conclusion: The present study revealed that G2013 could induce apoptosis in the liver cancer model. Therefore, based on these findings, G2013 might be considered as a therapeutic option in cancer therapy.

Temporal prophecy for proving temporal properties of infinite-state systems

Various verification techniques for temporal properties transform temporal verification to safety verification. For infinite-state systems, these transformations are inherently imprecise. That is, for some instances, the temporal property holds, but the resulting safety property does not. This paper introduces a mechanism for tackling this imprecision. This mechanism, which we call temporal prophecy, is inspired by prophecy variables. Temporal prophecy refines an infinite-state system using first-order linear temporal logic formulas, via a suitable tableau construction. For a specific liveness-to-safety transformation based on first-order logic, we show that using temporal prophecy strictly increases the precision. Furthermore, temporal prophecy leads to robustness of the proof method, which is manifested by a cut elimination theorem. We integrate our approach into the Ivy deductive verification system, and show that it can handle challenging temporal verification examples.

On the Versatility of Bracha’s Byzantine Reliable Broadcast Algorithm

G. Bracha presented in 1987 a simple and efficient reliable broadcast algorithm for [Formula: see text]-process asynchronous message-passing systems, which tolerates up to [Formula: see text] Byzantine processes. Following an idea recently introduced by Hirt, Kastrato and Liu-Zhang (OPODIS 2020), instead of considering the upper bound on the number of Byzantine processes [Formula: see text], the present short article considers two types of Byzantine behavior: the ones that can prevent the safety property from being satisfied, and the ones that can prevent the liveness property from being satisfied (a Byzantine process can exhibit only one or both types of failures). This Byzantine differentiated failure model is captured by two associated upper bounds denoted [Formula: see text] (for safety) and [Formula: see text] for liveness). The article shows that only the threshold values used in the predicates of Bracha’s algorithm must be modified to obtain an algorithm that works with this differentiated Byzantine failure model.

Implicit Semi-Algebraic Abstraction for Polynomial Dynamical Systems

Semi-algebraic abstraction is an approach to the safety verification problem for polynomial dynamical systems where the state space is partitioned according to the sign of a set of polynomials. Similarly to predicate abstraction for discrete systems, the number of abstract states is exponential in the number of polynomials. Hence, semi-algebraic abstraction is expensive to explicitly compute and then analyze (e.g., to prove a safety property or extract invariants).In this paper, we propose an implicit encoding of the semi-algebraic abstraction, which avoids the explicit enumeration of the abstract states: the safety verification problem for dynamical systems is reduced to a corresponding problem for infinite-state transition systems, allowing us to reuse existing model-checking tools based on Satisfiability Modulo Theory (SMT). The main challenge we solve is to express the semi-algebraic abstraction as a first-order logic formula that is linear in the number of predicates, instead of exponential, thus letting the model checker lazily explore the exponential number of abstract states with symbolic techniques. We implemented the approach and validated experimentally its potential to prove safety for polynomial dynamical systems.

Fuzzy Genetic Algorithm Approach for Verification of Reachability and Detection of Deadlock in Graph Transformation Systems

model checking techniques are often used for the verification of software systems. Such techniques are accompanied with several advantages. However, state space explosion is one of the drawbacks to model checking. During recent years, several methods have been proposed based on evolutionary and meta-heuristic algorithms to solve this problem. In this paper, a hybrid approach is presented to cope with the SSE problem in model checking of systems modeled by GTS with an ample state space. Most of existence proposed methods that aim to verify systems are applied to detect deadlocks by graph transformations. The proposed approach is based on the fuzzy genetic algorithm and is designed to decline the safety property by verifying the reachability property and detecting deadlocks. In this solution, the state space of the system is searched by a fuzzy genetic algorithm to find the state in which the specified property is refuted/verified. To implement and evaluate the suggested approach, GROOVE is used as a powerful designing and model checking toolset in GTS. The experimental results indicate that the presented hybrid fuzzy method improves speed and performance by comparing other techniques