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Trace links between requirements and software artifacts provide available traceability information and in-depth insights for different stakeholders. Unfortunately, establishing requirements trace links is a tedious, labor-intensive and fallible task. To alleviate this problem, Information Retrieval (IR) methods, such as Vector Space Model (VSM), Latent Semantic Indexing (LSI), and their variants, have been widely used to establish trace links automatically. But with the widespread use of agile development methodology, artifacts that can be used to generate automatic tracing links are getting shorter and shorter, which decreases the effects of traditional IR-based trace link generation methods. In this paper, Biterm Topic Model–Genetic Algorithm (BTM–GA), which is effective in managing short-text artifacts and configuring initial parameters, is introduced. A hybrid method VSM[Formula: see text]BTM–GA is proposed to generate requirements trace links. Empirical experiments conducted on five real and frequently-used datasets indicate that (1) the hybrid method VSM+BTM[Formula: see text]GA outperforms the others, and its results can achieve the “Good” level, where recall and precision are no less than 70% and 30%, respectively; (2) the performance of the hybrid method is stable and (3) BTM–GA can provide a number of “hard-to-find” trace links that complement the candidate trace links of VSM.

Nonlinear boundary control technique can offer superior dynamic behavior and eliminate the LCL-filter resonance in the grid-connected inverter. However, the chattering might be aroused by the distorted intracycle voltage information in the control law. It becomes worse when the nonlinear boundary controller is directly applied in three-phase three-wire inverter configuration. A hybrid current control scheme utilizing the decoupled predictive hysteresis capacitor current controller integrated with the linear grid current controller is proposed in the paper. By applying the 60° discontinuous pulse-width modulation scheme and using the virtual dual-buck decoupled structure, two separate sets of switching criteria for dictating the switching states of two specific half-bridge legs are formulated to avoid the interactions amongst phases. A small-signal ac model is also built to study the transfer characteristics of such hybrid current controlled inverter system. Simulation and experimental results have been offered to evaluate the effectiveness of the proposed method. Both results meet the theoretical predictions.

Nonlinear boundary control technique can offer superior dynamic behavior and eliminate the LCL-filter resonance in the grid-connected inverter. However, the chattering might be aroused by the distorted intracycle voltage information in the control law. It becomes worse when the nonlinear boundary controller is directly applied in three-phase three-wire inverter configuration. A hybrid current control scheme utilizing the decoupled predictive hysteresis capacitor current controller integrated with the linear grid current controller is proposed in the paper. By applying the 60° discontinuous pulse-width modulation scheme and using the virtual dual-buck decoupled structure, two separate sets of switching criteria for dictating the switching states of two specific half-bridge legs are formulated to avoid the interactions amongst phases. A small-signal ac model is also built to study the transfer characteristics of such hybrid current controlled inverter system. Simulation and experimental results have been offered to evaluate the effectiveness of the proposed method. Both results meet the theoretical predictions.

To ease the heavy burden of inverter control, including line current regulation, harmonic current suppression, filter resonance suppression, grid distortion suppression, phase locked loop etc., the study proposes a master–slave current regulation method for an LCL-filter-based grid-connected inverter operating under variable grid condition. The proposed system is composed of a grid-connected voltage-source inverter (GC-VSI) in series with a bidirectional voltage-source converter (B-VSC) at the inverter output. The GC-VSI is responsible for line current regulation, while the B-VSC takes charge of harmonic current suppression and grid impedance cancellation. Owing to low volt-ampere of the B-VSC, the efficiency of the inverter system is not sacrificed. To confirm its validity, a simulation platform with the proposed inverter system has been built. The simulation results demonstrate the performance enhancement of the proposed inverter system operating under different grid conditions.

Requirements traceability (RT) is a core activity in Requirements Engineering. Various types of RT technologies have been extensively studied for decades. In this paper, we present a systematic literature review from 114 papers between 2006 and 2016 on RT techniques. We summarized 10 major challenges in current RT activities, and categorized existing RT techniques into 6 groups and 25 sub-groups. Moreover, we built mapping relations between these challenges and techniques, and identified 7 potential future research directions. Based on 83 empirical studies, the evaluations for technology transfer are conducted. The main conclusions are: (1) The “trustworthy” and “automated” challenges are the most widely investigated ones, while “scalable”, “coordinated”, “dynamic” and “lightweight” challenges receive much less attention; (2) “Trace link generation”, especially information retrieval-based (IR-based) methods, are the most studied techniques; (3) IR-based methods have the most potential to be adopted by industry, as they have been validated from multiple viewpoints; (4) Seven promising future research directions are identified, which include developing scalable, dynamic and lightweight tracing techniques, introducing new approaches in other disciplines to meet the RT challenges, improving the express ability of trace links, promoting the industry adoption of RT technologies and developing new techniques to support developers’ coordination.

There are many types of dependencies between software requirements, such as the contributions dependencies (Make, Some+, Help, Break, Some-, Hurt) and business dependencies modeled in the i * framework. However, current approaches for prioritizing requirements seldom take these dependencies into consideration, because it is difficult for stakeholders to prioritize requirements considering their preferences as well as the dependencies between requirements. To make requirement prioritization more practical, a method called DRank is proposed. DRank has the following advantages: 1) a prioritization evaluation attributes tree is constructed to make the ranking criteria selection easier and more operable; 2) RankBoost is employed to calculate the subjective requirements prioritization according to stakeholder preferences, which reduces the difficulty of evaluating the prioritization; 3) an algorithm based on the weighted PageRank is proposed to analyze the dependencies between requirements, allowing the objective dependencies to be automatically transformed into partial order relations; and 4) an integrated requirements prioritization method is developed to amend the stakeholders’ subjective preferences with the objective requirements dependencies and make the process of prioritization more reasonable and applicable. A controlled experiment performed to validate the effectiveness of DRank based on comparisons with Case Based Ranking, Analytical Hierarchy Process, and EVOLVE. The results demonstrate that DRank is less time-consuming and more effective than alternative approaches. A simulation experiment demonstrates that taking requirement dependencies into consideration can improve the accuracy of the final prioritization sequence.

The HomyGene19+14Y System (HG19+14Y) is a PCR-based amplification kit that enables typing of 18 autosomal short tandem repeat (STR) loci (i.e., CSF1PO, D2S1338, D3S1358, D5S818, D6S1043, D7S820, D8S1179, D12S391, D13S317, D16S539, D18S51, D19S433, D21S11, FGA, Penta E, TPOX, TH01, vWA), 14 widely used Y chromosome STR (Y-STR) loci (Y_GATA_H4, DYS385a/b, DYS389I/II, DYS390, DYS391, DYS392, DYS393, DYS438, DYS439, DYS456, DYS458, DYS635), and amelogenin. This multiplex system was designed for the simultaneous analysis of amelogenin-Y allele mutation, single-source searches, kinship (including familial searching), mixture profiles, international data sharing, and other forensic applications. In this study, the multiplex system was validated for sensitivity, specificity, DNA mixtures, stability, precision, stutter, reproducibility, parallel tests, PCR-based conditions, and population analysis according to the Scientific Working Group on DNA Analysis Methods (SWGDAM) developmental validation guidelines. A total of 212 alleles were detected for the 18 autosomal STR loci among 528 Guangdong Han individuals, and 431 haplotypes were found for 14 Y-STRs among 452 unrelated males. The combined match probability (CMP) of the HG19+14Y System was calculated as 2.39 × 10−29. All the validation results showed that the HG19+14Y System would be a robust, reliable, highly polymorphic, and informative forensic kit.

Due to the existence of unknown grid impedance, the grid-connected inverter interacts with the grid and other distributed multiple paralleled inverters at the point-of-common-coupling (PCC). Such interaction challenges the system stability and the power quality especially when the inverter is with an LCL filter. A low-loss grid decoupling mechanism is proposed to counteract the effects of grid impedance in a three-phase grid connected inverter. It is composed of dual PCC voltage feedforward mechanisms, in which one is inserted at the inverter controller and the other is involved in the voltage regulation of an additional bidirectional dc/ac voltage source converter (B-VSC). The outputs of the B-VSC are connected in series with the ac filter capacitors while its inputs are provided with dc capacitors at the inverter dc bus. Because of small volt-ampere (VA) rating, the system efficiency is not sacrificed by the B-VSC. To validate its effectiveness, a three-phase inverter prototype with the proposed grid decoupling mechanism is verified successfully in the simulation.

Context-aware applications are becoming increasingly popular as they can adapt their behaviors to situations. However, the modeling of context-aware requirements is challenging owing to the inherent complexity and dynamicity of the context. Therefore, learning from existing studies can help academia and industry overcome the challenges. The primary objectives of this study are as follows: (1) survey the state-of-the-art of context-aware requirements modeling; (2) determine the challenges in context-aware requirements modeling and the extent to which the challenges have been addressed; (3) explore the future research directions of context-aware requirements modeling. We adopt the method of systematic literature review to retrieve relevant studies and extract available data aimed at the objectives. Seventy-two studies are finally selected. After data synthesis, we identify 4 categories of 13 challenges in context-aware requirements modeling. Based on the findings, we analyze the extent to which the challenges have been addressed and suggest future research directions.

Using AGCU Y24 Plus PCR Amplification Kit, 32 Y short tandem repeat (STR) loci were analyzed in 355 unrelated male participants of Meizhou city in Guangdong Province of China. By analyzing 341 different haplotypes, it was found that haplotype diversity (HD) and discrimination capacity (DC) were 0.9995 and 0.9605, respectively. Population relationships were analyzed by comparing Hakka population with ten other populations. The results indicate that Meizhou Hakka population was closely related to Guangdong Han population. These data were valuable for both forensic applications and population genetics.

The ultimate goal for researchers to develop a requirements traceability (RT) technology is transferring it from academy to industry. Academic researchers and industrial practitioners both expect that more and more technologies can be transferred. However, there is always a wide gap between RT research and practice. In this thesis, I'll propose a novel model that focuseson evaluating the RT technologies transfer maturity. A reasonable maturity evaluation model is proposed to measure to what extent an academic RT technology must achieve before it is able to be transferred to industry. Based on the model, an initial progress is made in selecting a suitable RT technology for industrial practitioners.