Parallel Test Prioritization

Although regression testing is important to guarantee the software quality in software evolution, it suffers from the widely known cost problem. To address this problem, existing researchers made dedicated efforts on test prioritization, which optimizes the execution order of tests to detect faults earlier; while practitioners in industry leveraged more computing resources to save the time cost of regression testing. By combining these two orthogonal solutions, in this article, we define the problem of parallel test prioritization, which is to conduct test prioritization in the scenario of parallel test execution to reduce the cost of regression testing. Different from traditional sequential test prioritization, parallel test prioritization aims at generating a set of test sequences, each of which is allocated in an individual computing resource and executed in parallel. In particular, we propose eight parallel test prioritization techniques by adapting the existing four sequential test prioritization techniques, by including and excluding testing time in prioritization. To investigate the performance of the eight parallel test prioritization techniques, we conducted an extensive study on 54 open-source projects and a case study on 16 commercial projects from Baidu , a famous search service provider with 600M monthly active users. According to the two studies, parallel test prioritization does improve the efficiency of regression testing, and cost-aware additional parallel test prioritization technique significantly outperforms the other techniques, indicating that this technique is a good choice for practical parallel testing. Besides, we also investigated the influence of two external factors, the number of computing resources and time allowed for parallel testing, and find that more computing resources indeed improve the performance of parallel test prioritization. In addition, we investigated the influence of two more factors, test granularity and coverage criterion, and find that parallel test prioritization can still accelerate regression testing in parallel scenario. Moreover, we investigated the benefit of parallel test prioritization on the regression testing process of continuous integration, considering both the cumulative acceleration performance and the overhead of prioritization techniques, and the results demonstrate the superiority of parallel test prioritization.

Prediction and risk stratification from hospital discharge records based on Hierarchical sLDA

Background The greatly accelerated development of information technology has conveniently provided adoption for risk stratification, which means more beneficial for both patients and clinicians. Risk stratification offers accurate individualized prevention and therapeutic decision making etc. Hospital discharge records (HDRs) routinely include accurate conclusions of diagnoses of the patients. For this reason, in this paper, we propose an improved model for risk stratification in a supervised fashion by exploring HDRs about coronary heart disease (CHD). Methods We introduced an improved four-layer supervised latent Dirichlet allocation (sLDA) approach called Hierarchical sLDA model, which categorized patient features in HDRs as patient feature-value pairs in one-hot way according to clinical guidelines for lab test of CHD. To address the data missing and imbalance problem, RFs and SMOTE methods are used respectively. After TF-IDF processing of datasets, variational Bayes expectation-maximization method and generalized linear model were used to recognize the latent clinical state of a patient, i.e., risk stratification, as well as to predict CHD. Accuracy, macro-F1, training and testing time performance were used to evaluate the performance of our model. Results According to the characteristics of our datasets, i.e., patient feature-value pairs, we construct a supervised topic model by adding one more Dirichlet distribution hyperparameter to sLDA. Compared with established supervised algorithm Multi-class sLDA model, we demonstrate that our proposed approach enhances training time by 59.74% and testing time by 25.58% but almost no loss of average prediction accuracy on our datasets. Conclusions A model for risk stratification and prediction of CHD based on sLDA model was proposed. Experimental results show that Hierarchical sLDA model we proposed is competitive in time performance and accuracy. Hierarchical processing of patient features can significantly improve the disadvantages of low efficiency and time-consuming Gibbs sampling of sLDA model.

Numerical simulation of crashworthiness parameters for design optimization of an automotive crash-box

Automotive manufacturers rely on rigorous testing and simulations to construct their vehicles durable and safe in all aspects. One such vital factor is crash safety, otherwise known as crashworthiness. Crash tests are conventional forms of non-destructive methods to validate the vehicle for its crashworthiness and compatibility based on different operating conditions. The frontal impact test is the most primary form of crash test, which focuses on improving passenger's safety and comfort. According to NHTSA, a vehicle is rated based on these safety criteria, for which automobile manufacturers conduct a plethora of crash-related studies. Numerical simulation aids them in cutting down testing time and overall cost endured by providing a reliable amount of insights into the process. The current study is aimed at improving the crashworthiness of a crash box in a lightweight passenger car, such that it becomes more energy absorbent in terms of frontal impacts. All necessary parameters such as energy absorption, mean crush force, specific energy absorption, crush force efficiencies are evaluated based on analytical and finite element methods. There was a decent agreement between the analytical and simulation results, with an accuracy of 97%. The crashworthiness of the crash box was improved with the help of DOE-based response surface methodology (RSM). The RSM approach helped in improving the design of the crash box with enhanced EA & CFE by 30% and 8.8% respectively. The investigation of design variables on the energy absorption capacity of the thin-walled structure was also done. For the axial impact simulations, finite element solver Virtual Performance Solution − Pam Crash from the ESI group is used.

Antiparasitic Activity of Single Solanum ferox Extract and Concoction with Zingiber zerumbet and Boesenbergia pandurata Extracts to Control Argulus sp. on Goldfish (Cyprinus carpio)

Argulus is an ectoparasite that frequently infects goldfish, with severe effects and a high death rate. The use of plant extracts has been widely reported to have antiparasitic activities, including one of the solasodine compounds in sour eggplant extracts. This research evaluated the antiparasitic activities of Compositions A (Solanum ferox and Zingiber zerumbet extract at 400 and 200 ppm, respectively), B (SFE and Boesenbergia pandurata at 900 ppm), and C (single Solanum ferox at 400 ppm). The research stages comprised 1) isolation and analysis of solasodine content in sour eggplant extracts and its extract composition, 2) in vitro antiparasitic activities on Argulus sp. at doses of 50 and 100 ppm with a testing time of 60–240 minutes, and 3) in vivo antiparasitic activities on Argulus sp. on goldfish at a dose of 100 ppm and observation for 2–12 hours of medication. The results showed that sour eggplant extracts had a solasodine concentration of 7.151 mg/L, whereas the derivative compositions A, B, and C were 656, 485, and 295 ppm, respectively. The in vitro testing demonstrated that composition A was effective for killing approximately 80–100% of Argulus, whereas compositions B and C killed 80–90% and 60–70%, respectively. Viewed from the effectiveness for killing parasites, the result was excellent (above 50%). The in vivo medication test was continued using three extract compositions at a dose of 100 ppm. Compositions A, B, and C were found to be capable of releasing 81.33, 75.67, and 71.00 arguli, respectively, per fish. We concluded that the single SFE extract and a concoction with BPE and ZZE had reasonable antiparasitic activity, whereas the concoction of SFE and ZZE killed more Argulus parasites at a higher rate.

Comparative quantification of focal and diffuse visual field loss by the SPARK Precision threshold algorithm and SITA

Purpose The aims of this paper were to examine focal and diffuse visual field loss in terms of threshold agreement between the widely used SITA Standard Humphrey Field Analyser (HFA) threshold algorithm with the SPARK Precision algorithm (Oculus Twinfield 2). Methods A total of 39 treated glaucoma patients (34 primary open angle and 5 primary angle closure glaucoma) and 31 cataract patients without glaucoma were tested in succession with the Oculus Twinfield 2 (Oculus Optikgeräte GmbH, Wetzlar, Germany) using the SPARK Precision algorithm and with the HFA 3 (Carl Zeiss Meditec, Dublin, CA) using the 30–2 SITA Standard algorithm. Results SPARK Precision required around half the testing time of SITA Standard. There was a good correlation between the MS of the two threshold algorithms but MD and PSD were significantly less severe with SPARK Precision in both glaucoma (focal field loss) and cataract (diffuse field loss) groups (p < 0.001). There was poor agreement for all global indices (MS, MD and PSD) between the two algorithms and there was a significant proportional bias of MD in the glaucoma group and PSD in both glaucoma and cataract groups. The pointwise sensitivity analysis yielded higher threshold estimates in SPARK Precision than in SITA Standard in the nasal field. Classification of glaucoma severity using AGIS was significantly lower with SPARK Precision compared to SITA Standard (p < 0.001). Conclusion SITA renders deeper defects than SPARK. Compared to the SITA Standard threshold algorithm, SPARK Precision cannot quantify early glaucomatous field loss. This may be due to the mathematical linear interpolation of threshold sensitivity or deeper scotomas due to the plateau effect caused by the reduced dynamic range of the Twinfield 2 perimeter. Although not of clinical significance in early glaucoma, the plateau effect may hinder the long-term follow-up of patients during disease progression.

Influence of Waste Fly Ash on the Rheological Properties of Fresh Cement Paste and the Following Electrical Performances and Mechanical Strengths of Hardened Specimens

Waste fly ash (WFA) is a kind of solid waste without reasonable disposition. The WFA with active substance can promote the cement hydration, therefore, WFA may enhance the mechanical strengths of cement-based materials. In this paper, the rheological properties (slump flow and plastic viscosity) of fresh cement paste with WFA ranging from 0% to 25% by mass ratio of cement were studied. The alternating current (AC) electrical resistance and direct current (DC) resistance time curves were determined. The AC impedance spectroscopy curves of the specimens cured for 1 day and 28 days were obtained. Finally, the mechanical strengths of hardened cement paste cured for 1 day, 3 days, 7 days, and 28 days were tested. The results showed that the slump flow was decreased and the plastic viscosity was increased by the addition of WFA and the increasing curing time. The AC electrical resistance increased in the form of the quadratic function with the cuing age. Meanwhile, the addition of WFA demonstrated an enhancing effect on the electrical conduction of cement paste. The variation rate of DC electrical resistance during the testing time increased with the increasing dosages of WFA and the curing age. The mechanical strengths increased with the addition of curing time and the content of WFA. The increasing rate of mechanical strengths increased with the addition of WFA (0~15%) and decreased with curing time. However, when the dosage of WFA increased from 15% to 25%, the increasing rate decreased.

Removal of the Cervical Spine Collar from Alpine Extrication and Evacuation Skiing Rescue Spinal Motion Restriction Protocols: A Biomechanical Controlled Study in Real-Life Mountain Conditions with a High-Fidelity Mannequin

Background: Alpine skiing rescues are unique because of the mountainous environment and risks of cervical spine motion (CSM) induced during victims’ extrication (EX) and downhill evacuation (DE). Current pre-hospital guidelines recommend the application of full spinal immobilization using various orthotic devices such as cervical collars (CC) when mobilizing and transfer+ring a victim with a suspected spine injury. The biomechanical benefits of applying CC in terms of spinal motion restriction during simulated alpine rescue are undocumented. Methods: Observational design of CSM measurement on a high-fidelity simulation mannequin with a motion sensors-instrumented cervical spine during simulated alpine skiing EX and DE. A total of 32 EXs and 4 DEs on different slope conditions were performed by six experienced active ski patrollers at a Canadian ski resort. The primary outcome was the 3D excursion vector (PeakΔθ) of the mannequin’s head. The secondary objectives were the time to extrication completion (tEX) depending on CC use and to identify which EX event is more likely to induce CSM. Results: PeakΔθ recorded during flat terrain EX using CC was 11.71° +/- 3.61° compared to 16.00° +/- 7.93° using MILS, and 18.29° +/- 9.78° for CC versus 17.90° +/- 4.16° using MILS on a steep slope. PeakΔθ with CC or using MILS during EXs were equivalent according to a 10 degrees non-inferiority hypothesis testing. Time to extrication completion (tEX) was significantly higher using CC as opposed to MILS for both flat and steep terrain conditions (100.6s vs. 219.2s and 106.2s vs. 268.8s longer respectively, 95% confidence interval). During DEs, CSM with and without CC across all terrain conditions were negligible (<5°). Task analysis during EX showed that when CC is used, its installation induces the highest CSM. When EXs are done using MILS without CC, the logroll initiation is the manipulation inducing the highest risk of CSM. Conclusion: For experienced ski patrollers, the biomechanical benefits of motion restriction provided by CC over MILS during alpine skiing rescues were found to be at best marginal and CC use negatively affected rescue time. Systematic use of CC during alpine rescue should be reconsidered.

Dynamic Response Prediction of Bi-State Emission of Quantum Dot Lasers Based on Machine Learning

Dual-state emission is a common and important phenomenon which takes place in semiconductor Quantum Dot Lasers at different temperature and operating conditions usually investigated from microscopic carrier interaction modeling or even rate-equations based approaches. In this study, we revisit the topic, but the investigation is here performed from a system identification perspective; we built black-box models based on artificial neural networks approach, using the Multilayer Perceptron, the Extreme Learning Machine and a hybrid Echo State Network - Extreme Learning Machine. As a case study, we focused on switch-on transient and its prediction. The study revealed the model was able to separate and to predict, from the solely total power, without using any QDL design parameters, the optical power around the ground state and first excited state lasing lines of InAs/InGaAs quantum dot laser. The error performance was low as a RMSE of 2.81 μW and MAPE of 0.50% with processing time (training and testing time) of 15.27 s, enabling the alternative model to be used in optical filtering instrumentation as low-resolution and low-cost filters for applications in which it is not economically viable to use a spectrum analyzer, which can be replaced by a simple optical power meter.

Cavitation erosion damage of self-fluxing NiCrSiB hardfacings deposited by oxy-acetylene powder welding

This paper comparatively investigates the cavitation erosion damage of two self-fluxing NiCrSiB hardfacings deposited via the oxy-acetylene powder welding method. Examinations were conducted according to the procedure given by ASTM G32 standard. In order to research cavitation erosion (CE), the vibratory apparatus was employed. The cavitation damaged surfaces were inspected using a scanning electron microscope, optical microscope and surface profilometer. The hardness of the A-NiCrSiB hardfacing equals 908HV while that of C-NiCrSiB amounts to 399HV. The research showed that the CE resistance of C-NiCrSiB is higher than that of A-NiCrSiB. The results demonstrate that in the case of multiphase materials, like the NiCrSiB hardfacings, hardness cannot be the key factor for cavitation erosion damage estimation whereas it is strongly subjected to material microstructure. In order to qualitatively recognise the cavitation erosion damage of the NiCrSiB self-fluxing hardfacings at a given exposure time, the following factors should be respected: physical and mechanical properties, material microstructure and also material loss and eroded surface morphology, both stated at specific testing time. The general idea for the cavitation erosion damage estimation of the NiCrSiB oxy-acetylene welds was presented.

A novel design for hardware interface board with reduced resource utilization

The final cost of an integrated circuit (IC) is proportional to its testing time. One of the main goals of test engineers when building an IC test solution is to reduce test time. Reduction of Test time is achieved by multi-site testing where multiple ICs are tested simultaneously using automated test equipment (ATE). During multi-site testing, if a certain test requires abundant resources, it is accomplished by testing one set of ICs at a time while the other ICs remain idle, thus lengthening the total test time. In digital-analog hybrid ICs, both analog and digital tests need to be performed, increasing the tester resource requirement and causing digital resource shortage. This paper describes a hardware interface board (HIB) design for a test case of a digital-analog IC on Teradyne’s ETS-364 ATE. The HIB's design allows the ATE to perform multi-site I²C based tests, which usually require lot of tester resources, utilizing only two digital resources and one measurement resource. This design achieves halving the I2C test time while lowering the number of resources necessary for multi-site testing compared to set-by-set testing. The proposed work has achieved up to 90.625% of resource reduction for multisite testing for a single test.