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K-means and its various hybrids are popularly used for software fault prediction. K-means++ is a hybrid clustering algorithm which overcomes major issue of getting stuck at local optima. Here, in this paper swarm intelligence-based hybrid techniques viz. cuckoo algorithm which improves the fitness function and bat algorithm which swarms with varying speeds are used on k-means++ algorithm to design a new hybrid clustering technique. KBat++ algorithm is a designed hybrid clustering technique with increased convergence rate which is further improvised using robust cuckoo swarm intelligent technique on this designed algorithm to generate CKBat++ algorithm which is predicted to generate optimised high-quality clusters. Experiments are performed using open-source UCI and promise datasets to implement and compare performance of designed algorithms with KBat and k-means++ algorithms. Accuracy, cluster quality check, CPU time etc. are used for performance comparisons. Results indicate that the designed technique which is used to predict and categorise software faults into faulty and non-faulty clusters to avoid errors and increase software reliability, is fairly better in performance than its counterparts.

The present article reports the combustion and emission characteristics of different monocyclic and polycyclic aromatics in a distributed combustion regime. Fuel blends based on five different aromatics, namely, ethylbenzene, α-methylstyrene, tetralin, indene, and methylnaphthalene, are investigated in a lab-scale distributed combustor at a thermal input of 30 kW, and the results are compared with commercial kerosene fuel. The fuel blends include a mixture of a base fuel, n-decane, and single added aromatics. The combustor is also numerically modeled using a chemical-equilibrium-based nonpremixed droplet combustion model for both monocyclic and polycyclic aromatic blended fuels. It is observed that the proper selection of aromatics in base fuel significantly affects the combustor performance. Fuel blends based on monocyclic aromatics lead to an increased level of dilution and, consequently, a more uniform thermal field. Better spray characteristics of monocyclic aromatic fuel blends in comparison to kerosene and polycyclic aromatics result in reduced levels of gaseous and acoustic emissions. This helps create a more favorable environment for the formation of lower pollutant emissions. Unburned hydrocarbon emissions approach zero levels for ethylbenzene and α-methylstyrene fuel blends. It is observed that both the aromatic type and its overall content are responsible for particulate matter (PM) emissions. A wise selection of a novel aromatic-based fuel blend results in relatively lower PM emission levels in comparison to kerosene. Monocyclic aromatic-based fuel blends have an aromatic content similar to kerosene, and they produce relatively lower PM emissions. It is observed that through a wise selection of aromatic compounds and their concentration, both the objectives of future gas turbines, i.e., performance in terms of seal swell and lower gaseous emissions, can be achieved fastidiously.

Fuel formulation with particular selection of fuel components is a promising approach that offer the reduction of harmful emissions without altering the combustion system performance. Each fuel component has their own combustion characteristics and hence contribution in emissions. Aromatic is one of the main component of fossil based fuels and have a strong correlation with the formation of PM emissions. Besides aromatics presence in fuel is essential for compatibility of fuel with combustion system and maintaining the energy density of the fuel. In this regard, a Rolls Royce combustor rig was used to test 16 aromatics blended with jet fuels in three different proportions. Moreover, a novel approach of flame luminosity imaging is employed to measure the PM emissions through the soot propensity profile. The results show that PM emissions increase with the proportional increase of aromatics. The di- and cyclo-aromatics produced significantly higher PM emissions compared to alkyl-benzenes. 3-isopropylcumene has the tendency to lowest PM formation and thus is a consideration as a selection of aromatic type in future fuels for lower PM emissions. Furthermore, it was also observed that PM number concentration measured by extractive method with DMS500 instrument correlates well with imaging methods for all the tested fuels. The present study provides an information of particular selection of aromatic for future fuel development.

Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes, the zinc-dependent endopeptidases involved in the degradation of extracellular matrix (ECM) and releasing growth factors and cytokines residing in ECM. Amongst 23 types of MMPs, an isomer called MMP-9 has been found to play a vital role in angiogenesis, and its overexpression leads to cancer. Inhibition of MMP-9 could be very useful for the treatment of cancer.

The escalating prices, rapid diminution of fossil fuels, tenacious regulations of the authorities, etc. enforced towards the alternate biogenic fuel for lubrication. The present study assessed the lubricity characteristics of Phyllanthus Emblica seed oil based lubricants by using a pin on disc (POD) tester. The design of experimentations has been carried out using response surface methodology (RSM). The value of parameters such as blend ratio, load and sliding speed ranges from 0 to 20%, 50 to 100 N and 1.3 to 3.8 m/s, respectively, are used to assess the value of specific wear rate (SWR) and coefficient of friction (COF). Test results illustrate that the adhesive wear occurred during the experiments. It has been observed that AB10 shows the probable results in terms of wear and friction characteristics as compared to other lubricant variants at low load and high sliding velocity conditions and perform as an excellent lubricant additive. This contributes towards the replacement of petroleum based lubricants. Analytical ferrography and total acid number (TAN) analysis of the used oil was also done to study the wear debris in the oil.

Biodiesel is a promising fuel which shows potential and gradually received attention as a best alternate feedstock for diesel engine. Previous investigations have shown that use of double biofuels in a diesel engine can be a promising aspect for complete elimination of diesel from compression ignition engines which will decrease our dependency on fossil fuels. The tribological performance of injection system is primarily based on the lubricity characteristics of the fuel. So, it is imperative to a more diversified research about the impact of using double biofuels in engine. In the present investigation, different biodiesel-oil blends were investigated using the ASTM D6079 by the reciprocatory friction monitor. The effect of temperature variation on lubricity characteristics was also studied. The biodiesel-oil blends shows improvement in results as compared to diesel. Biodiesel is prone to oxidation due to availability of unsaturation in their moieties. The effects of oxidation on lubricity characteristics were also studied. It was also found that the operating conditions collectively affected the lubricity characteristics of tested feedstocks.

The investigation aims to evaluate the impacts of commercial gasoline and gasoline surrogates on energy and exergy efficiencies in a spark-ignition (SI) engine. In this investigation, a new approach for formulating next-generation gasoline surrogates is investigated through testing these surrogates in a multi-cylinder SI engine. Energy and exergy analyses were carried out using the primary reference fuel-methylcyclohexane (PRF-MCH) blend (82.88% iso-octane + 9.16% n-heptane + 7.96% methylcyclohexane), primary reference fuel with 1,2,4-trimethylbenzene (PRF-1,2,4-TMB) blends (76% iso-octane + 9% n-heptane + 15% 1,2,4-trimethylbenzene and 61% iso-octane + 9% n-heptane + 30% 1,2,4-trimethylbenzene), and commercially available gasoline (gasoline) in an SI engine. The engine investigation results show that the PRF-MCH blend is a promising surrogate to reproduce the gasoline fuel engine characteristics such as combustion and emission characteristics of gasoline fuel. The detailed experiments were executed at the SI-engine speed conditions of 1500 rpm and 2500 rpm. It is found that PRF-MCH blend energy-exergy efficiencies are comparable to commercially available gasoline. It can also be concluded that engine testing in terms of energy-exergy analyses for proposed gasoline surrogates provides a qualitative and quantitative understanding of combustion behavior, emission characteristics, assessment of the effectiveness, and useful work potential gasoline surrogates.

Due to a wide range of attacks possible on the internet, abundance of security solutions exists in the market today. In spite of this, distributed denial of service (DDoS) attack is still considered irrepressible, as none of the present-day solutions seems to completely eradicate its existence. The most sophisticated form of this attack, application-layer DDoS attack, is on the rise seeking to its surging frequency in recent years. With a primary focus on their detection and mitigation, the researchers have made significant contributions toward the related literature. We begin with introducing application-layer DDoS attacks followed by an analysis of the recent contributions in a nutshell. Subsequently, the underlying mechanism behind the application-layer DDoS attacks is discussed to apprehend its effect on traditional web server architecture. Finally, two independent exhaustive simulations are carried out to evaluate the impact of such attacks on the performance of a web server from multiple perspectives. Multifarious experimental designs corresponding to different attack intensities and server performance parameters are exercised during our first simulation scenario in order to report diverse possible scenarios. The second simulation scenario examines three well-known application-layer DDoS attack strategies that an attacker usually adopts in order to instigate an application-layer DDoS attack.

Context: Tangled commits are changes to software that address multiple concerns at once. For researchers interested in bugs, tangled commits mean that they actually study not only bugs, but also other concerns irrelevant for the study of bugs. Objective: We want to improve our understanding of the prevalence of tangling and the types of changes that are tangled within bug fixing commits. Methods: We use a crowd sourcing approach for manual labeling to validate which changes contribute to bug fixes for each line in bug fixing commits. Each line is labeled by four participants. If at least three participants agree on the same label, we have consensus. Results: We estimate that between 17% and 32% of all changes in bug fixing commits modify the source code to fix the underlying problem. However, when we only consider changes to the production code files this ratio increases to 66% to 87%. We find that about 11% of lines are hard to label leading to active disagreements between participants. Due to confirmed tangling and the uncertainty in our data, we estimate that 3% to 47% of data is noisy without manual untangling, depending on the use case. Conclusion: Tangled commits have a high prevalence in bug fixes and can lead to a large amount of noise in the data. Prior research indicates that this noise may alter results. As researchers, we should be skeptics and assume that unvalidated data is likely very noisy, until proven otherwise.

Among the alternate resources, biodiesel has shown a ray of hope for replacing diesel, thus decreasing the harmful emissions generated by the compression ignition engine. The present study covers the important aspects of fuel effect on engine wear. Along with the better combustion, performance, and emission tests, it is also equally important to study the effect of the fuel on different parts. To study the effect of fuel on engine wear, there are standards available to check the tribological performance of the fuel. The present study was done as per the ASTM D4172 standard. The study includes the friction and wear characteristics of Jasmine biodiesel and its blends (JB100, JB75, JB50 and JB25), compared to those of diesel. Each test is performed for 3600 s at a fixed speed of 1200 rpm at different loads (147 N and 392 N) and temperatures (45, 60 and 75 °C). Results reveal that the lubricity of tested fuels increases with the increase in biodiesel concentrations. The average wear scar diameter (WSD) is observed to be around 8.89% higher in diesel than that in JB100 at higher load and higher temperature conditions. Adhesive or corrosive wear and crack formation occur at high load and temperature conditions. In contrast, abrasive wear occurs at a low load and temperature, as analyzed with a scanning electron microscope.

Coupling measures are considered important due to their inherent relationships with external software quality attributes. The ongoing research on object oriented software quality has been focusing on devising dynamic metrics for software quality assessment because of their ability to capture the runtime behavior of software. A number of dynamic coupling metrics have been proposed in recent times to measure software quality. This paper is an attempt to fill in the gap between existing work and researchers by providing them essential knowledge about the dynamic coupling metrics, methodologies and techniques proposed in this area. This paper presents a survey of existing research related to dynamic coupling metrics for object oriented software systems. Metrics have been categorized according to some of their major characteristics such as dynamic analysis techniques, validation of metrics, relation with static metrics etc. The capability of these metrics in quantifying external software quality attributes is also studied. The survey found that very few dynamic coupling metrics have been proposed and most of the proposed metrics lack empirical validation limiting their applicability in software quality assessment.

Recent research in the field of object-oriented software engineering has been focusing on the usage of software metrics for the assessment of a product's quality. Software design coupling metrics include some of the most widely applicable metrics used in the modern software industry. Although static coupling metrics are used for analyzing the structural aspects of the object-oriented software systems, their inability to capture the behavioral aspects is well known and hence has given way to the evolution of their runtime counterparts i.e. the dynamic coupling metrics. Most of the dynamic coupling metrics proposed until now have not yet been empirically validated due to the high evaluation cost involved in the runtime metric data collection, hence limiting their practical application. This paper, as a part of our ongoing research on empirical validation of the dynamic coupling metrics, presents an empirical investigation into the static and dynamic CBO (Coupling Between Objects) metrics using some open source real world java applications. A set of criteria for the selection of sample benchmark applications required for the dynamic metrics validation has also been devised. A scenario based approach in combination with the appropriate statistical techniques has been used in an attempt to correlate the static and dynamic coupling metrics.

Conversion of solar energy into thermal energy using solar collectors is the most promising way for itsapplicability. Artificial roughness applied underside of the solar heat-collector is a preferably advantageous technique to enhance the solar air heater performance. In the present study, a comprehensive parametric analysis of the multi-V-ribs-with-symmetric-multi-gaps type of roughness elements (which employed over the heat-collector plate) has been conducted. Two novel roughness parameters (discreteness ratio and aspect ratio) are introduced and their impact is analyzed on thermo-hydraulic performance of the solar air heater (SAH). Moreover, relative roughness width, relative gap width, relative rib-height and relative rib-pitch impact are also assessed. The output parameter (i.e., Nusselt number and friction factor) has been estimated from the experimentally measured data under steady-state conditions. An increment of 6.46 times in Nusselt number along with 5.67 times in friction factor is observed in a comparison to a smooth SAH. The maximum thermo-hydraulic performance parameter for the present investigation is 4.24, which is comparatively higher. The generalized mathematical expressions for Nusselt number and friction factor are developed. The predicted results are found in the deviation of 7.28% and 8.45% for Nusselt number and friction factor.

Many Runtime/Dynamic metric suites for object-oriented software systems have been devised over the past decade. This paper introduces a new dynamic metric-based evaluation and analysis tool for Java and C++ software called DynaMetrics that is capable of evaluating and analyzing all the major dynamic metrics known till date. DynaMetrics also compares them with their static counterparts in order to find the usefulness of individual metric. The paper is part of our ongoing research on runtime/dynamic metrics for object-oriented software systems.

This paper presents a comprehensive review of the technical feasibility of biomass-derived combustible gaseous fuels and low-calorific-value biomass as a feedstock for combustion engines. The mixture of combustible gases (producer gas) can be generated from biomass and successively used for power generation from combustion engines. The producer gas can be used in dual fuel mode in compression-ignition engines. The present review covers the modifications suggested for the feasibility of producer gas as a feedstock in diesel engines. The effects of modification in diesel engine parameters, namely compression ratio, injection timing, and injection pressure, are extensively reviewed. This paper assesses the impact of these engine parameters on fundamental combustion processes with producer gas. There is a broad impression in the literature that the operation and performance of combustion engines are significantly impacted by using producer gas as a fuel. The impact of this feedstock on engine performance and tailpipe emissions is also covered. The effect of versatile management of pilot fuel, combustion chamber geometries, type of carburetors, and producer gas quantity on the engine characteristics are discussed.

Fossil fuel consumption provides a negative impact on the human health and environment in parallel with the decreased availability of this valuable natural resource for the future generations to use as a source of chemical energy for all applications in energy, power, and propulsion. The diesel fuel consumption in the transport sector is higher than the gasoline in most developing countries for reasons of cost and economy. Biodiesel fuel offers a good replacement for diesel fuel in compression ignition (CI) diesel engines. Earlier investigations by the authors revealed that a blend of 70% amla seed oil biodiesel and 30% eucalyptus oil (AB70EU30) is the favorable alternative renewable fuel blend that can be used as a fuel in diesel engines. With any fuel, air/fuel mixing and mixture preparation impact efficiency, emissions, and performance in CI engines. Minor adjustments in engine parameters to improve air/fuel mixing and combustion are deployable approaches to achieve good performance with alternative fuel blends in CI engines. This paper provides the role of a minor modification to engine parameters (compression ratio, injection timing, and injection pressure) on improved performance using the above mixture of binary fuel blends (AB70EU30). The results showed that the use of AB70EU30 in modified engine resulted in higher brake thermal efficiency and lower brake specific fuel consumption compared to normal diesel for improved combustion that also resulted in very low tailpipe emissions.

•Heat transfer augmentation in multiple curved arcs (with gap) ribbed solar air heater.•Experimentation is designed using response surface methodology.•ANOVA technique is used to obtain optimized thermal performance of solar air heater.•The optimum thermohydraulic performance parameter obtained is 3.85.•Quadratic correlation for Nusselt number and friction factor are developed.

This paper presents lubricating oil performance in a compression ignition (CI) engine fueled with a binary fuel blend of 70% aamla seed oil biodiesel and 30% eucalyptus oil (EU) on volume basis. This blended fuel was stable and congruent with engine-fuel system. Initially, the engine was operated with normal diesel fuel as per standard endurance test. The same endurance test was performed with the above binary biodiesel blended fuel in the engine under somewhat modified engine operational condition. The lubricating oil was examined at a specified interval to evaluate the impact of the fuel on lubricating oil properties. Quantification of various metal debris concentrations was carried out using inductive coupled plasma atomic emission spectroscopy. After experimentation, the lubricating oil samples were analyzed using analytical ferrography that showed lower wear debris concentrations from binary biodiesel blend than diesel fuel operated engine. The better lubricating property of binary biodiesel blended fuel resulted in lower wear and improved performance of engine parts. Relatively low wear and concentrations of all metal wear were found in the lubricating oil with binary biodiesel blended fuel engine revealed better performance of engine with this fuel blend. No technical problem was encountered during the long-term endurance tests with the binary biodiesel blended fuel under modified engine parameters.

The results obtained on wear assessment from a compression ignition (CI) engine fueled with a blend of 70% amla seed biodiesel (AB) and 30% eucalyptus oil (EU) on volume basis (called AB70EU30). The results showed stable engine operation and good operability of the engine-fuel system with the binary biodiesel fuel blend. The feasibility of this blend over a long-term endurance tests was explored. The specific assessment examination included the fate of cylinder head, pump plunger, injector nozzle, and piston crown, which affects the engine performance and engine life. The experimental results revealed better tribological performance characteristics with the binary fuel blend as compared to contemporary diesel fuel. No specific problem was encountered during the long-term endurance tests with the binary fuel blend using the modified engine parameters. The results show that the binary fuel mixture offers good potential for use as diesel fuel in CI engines while maintaining good performance and endurance.