Dynamic Testing Techniques of Non-Functional Requirements in Mobile Apps: A Systematic Mapping Study

Context: The mobile app market is continually growing offering solutions to almost all aspects of people’s lives, e.g., healthcare, business, entertainment, as well as the stakeholders’ demand for apps that are more secure, portable, easy to use, among other non-functional requirements (NFRs). Therefore, manufacturers should guarantee that their mobile apps achieve high-quality levels. A good strategy is to include software testing and quality assurance activities during the whole life cycle of such solutions. Problem: Systematically warranting NFRs is not an easy task for any software product. Software engineers must take important decisions before adopting testing techniques and automation tools to support such endeavors. Proposal: To provide to the software engineers with a broad overview of existing dynamic techniques and automation tools for testing mobile apps regarding NFRs. Methods: We planned and conducted a Systematic Mapping Study (SMS) following well-established guidelines for executing secondary studies in software engineering. Results: We found 56 primary studies and characterized their contributions based on testing strategies, testing approaches, explored mobile platforms, and the proposed tools. Conclusions: The characterization allowed us to identify and discuss important trends and opportunities that can benefit both academics and practitioners.

Dilemma in the Development of Modern Timber Architecture and Its Countermeasures

Under the context that “peak carbon emissions” and “carbon neutrality” are included in the overall plan for the construction of ecological civilization in China, this paper discusses the value of modern timber architecture as a form of low-carbon and environmental protection movement in the whole life cycle of the construction field. It mainly analyzes the reasons for the limited resources, misunderstandings of inherent concepts, the high cost of comprehensive construction, and the shortage of professionals. Based on that, several countermeasures have been proposed, such as perfecting relevant norms and policies, strengthening technology research and development as well as demonstration guidance, moderately developing forest resources, applying digital construction operation and maintenance technology, as well as cultivating compound professionals, all of which provide a reference for the development of ecological benefits in China’s construction industry.

Life Cycle Assessment of a Wall Made of Prefabricated Hempcrete Blocks

Hempcrete is a natural building material obtained mixing hemp shives (i.e., the woody core of the hemp plant) with a lime-based binder and water. Hempcrete as construction material is gaining increasing interest as the EU aims to achieve net zero emissions by 2050. This material has, in fact, the ability to uptake carbon dioxide from air (i.e., via carbonation) and to store carbon for long time. The goal of the present work is to deeper analyze the environmental profile of hempcrete, in order to assess its potentials in reducing emissions of construction sector. Specifically, Life Cycle Assessment (LCA) of a non-load-bearing wall made of hempcrete blocks is carried on. The analysis encompasses the whole life cycle from the extraction of raw materials to the end of the service life. The analyzed blocks are produced by an Italian company. Only aerial lime is used as binder, microorganisms are added to the blocks to accelerate carbonation. The impact on climate change is assessed through the GWP 100 method proposed by IPCC. Preliminary results reveal a nearly neutral carbon budget.

Circular Economy Development in the Construction Sector in Japan

The circular economy (CE) is about a system-level change towards sustainability, and it aims at keeping products, components, and materials at their highest utility and value at all times, covering both technical and biological cycles. This study aimed at exploring, discovering, describing, and synthesizing the characteristics of CE development in the construction sector in Japan based on the perspectives of sectoral organizations and focusing on the following themes: (1) sustainable production; (2) sustainable consumption; (3) creation and maintenance of value in a CE; (4) CE innovations; (5) CE of material and energy use; (6) technological, economic, and social barriers to CE; (7) CE guidance; and (8) specific CE aspects in the construction sector. This study applied a qualitative research approach, including a questionnaire survey as the specific method. This study addressed a gap in the research and helps to improve understanding of the CE development priorities based on the perspectives of organizations operating in or related to the construction sector in Japan. The findings indicate that the priority CE development focus areas in the construction sector in Japan encompass, for example, the use of sustainable and renewable raw materials; consumer awareness; and the design, use, and manufacturing of sustainable, recyclable, reusable, and repairable products, components, and materials. The barriers to CE that need to be overcome encompass, for example, the lack of general knowledge about circular economy opportunities and of seeing the “big picture” as well as issues related to economic benefits and the development of CE and sustainability-oriented products, components, and materials. Particularly important CE aspects in the construction sector include the maintenance of existing buildings; sustainability and the long-life cycles of products, components, and materials; CE-oriented product design; and sustainability criteria and cooperation between parties covering the whole life cycle of construction.

Digital Twin-Assisted Simulation of Complex Assembly Models in Descending Process and Implementation of Key Link Characterization

In this paper, the simulation and key link characterization of the complex assembly model step-down process are studied and analysed in depth using the digital twin approach, and the method is used in the practical process. The physical model step-down method MORA algorithm and its physical interpretation in various simplified cases are given, and the MORA method is improved on this basis. The concept of local activeness based on knot structure is introduced, and the process of model transformation and downscaling and decomposition based on local activeness is explained in detail. The high-fidelity mapping of solid equipment is completed in virtual space, which can accurately reproduce and predict the health state of engineering equipment throughout its life cycle, effectively avoiding the huge property losses and safety risks caused by early failure of vulnerable structures and providing a safe and stable working environment for offshore oil and gas production. With the prototype monitoring data as reference, the response surface method is used to identify the parameters of the finite element model of the hinge node, which improves the fidelity of the virtual model of the hinge node. Considering the friction coefficient changes and load characteristics during the degradation of the hinge node, the dynamics simulation conditions are set, and the operating states of the hinge node at different stages of its whole life cycle are simulated by using the high-fidelity virtual model of the hinge node, and the prediction model of the hot spot stress of the hinge node is established to monitor its in-position state in real time, and the operation and maintenance overhaul method based on the health state of the hinge node is proposed. The system is divided into four modules: multilevel inverse modelling of the assembly twin, statistical shape characterization and analysis of batch parts, optimization of fixture positioning and flexible assembly of thin-walled parts, and optimization of low-stress assembly of bolted joint structure, which verifies the feasibility of the method and provides guidance for the actual product forming process.

Research on Visual Management Technology of Tunnel Construction Process Based on BIM Technology

In order to achieve more efficient management of BIM technology in the field of tunnel construction, this paper took Zhuhai Dahengqinshan No. 1 Tunnel as the project background and studied the visualization management technology of tunnel construction process based on BIM technology. Firstly, we created the 3D geological model and tunnel BIM model by using Revit, 3dsmax, and other software. Secondly, the detailed design was carried out, and there was no gap in the model after the detailed design was checked by ABAQUS software. Then, we checked the problems between disciplines and conducted collision inspection in the model. Finally, we carried out the 4D construction progress simulation to solve the conflict between time and space in the whole life cycle of tunnel construction. The results revealed that the deepening design could optimize the design scheme of tunnel construction engineering. Collision inspection directly exposed problems such as unscientific site layout. 4D construction schedule management could not only realize the visualization of field construction process but also improve the quality of project management compared with traditional means. The research results provide technical experience for the visualization management of tunnel construction.

Real-Time Life-Cycle Monitoring of Composite Structures Using Piezoelectric-Fiber Hybrid Sensor Network

In this paper, an in situ piezoelectric-fiber hybrid sensor network was developed to monitor the life-cycle of carbon fiber-reinforced plastics (CFRPs), from the manufacturing phase to the life in service. The piezoelectric lead-zirconate titanate (PZT) sensors were inserted inside the composite structures during the manufacturing process to monitor important curing parameters, including the storage modulus of resin and the progress of the reaction (POR). The strain that is related to the storage modulus and the state of resin was measured by embedded fiber Bragg grating (FBG) sensors, and the gelation moment identified by the FBG sensors was very close to those determined by dynamic mechanical analysis (DMA) and POR. After curing, experiments were conducted on the fabricated CFRP specimen to investigate the damage identification capability of the embedded piezoelectric sensor network. Furthermore, a modified probability diagnostic imaging (PDI) algorithm with a dynamically adaptive shape factor and fusion frequency was proposed to indicate the damage location in the tested sample and to greatly improve the position precision. The experimental results demonstrated that the average relative distance error (RDE) of the modified PDI method was 68.48% and 46.97% lower than those of the conventional PDI method and the PDI method, respectively, with an averaged shape factor and fusion frequency, indicating the effectiveness and applicability of the proposed damage imaging method. It is obvious that the whole life-cycle of CFRPs can be effectively monitored by the piezoelectric-fiber hybrid sensor network.

A Content Review of Life Cycle Assessment of Nanomaterials: Current Practices, Challenges, and Future Prospects

This paper provides a comprehensive review of 71 previous studies on the life cycle assessment (LCA) of nanomaterials (NMs) from 2001 to 2020 (19 years). Although various studies have been carried out to assess the efficiency and potential of wastes for nanotechnology, little attention has been paid to conducting a comprehensive analysis related to the environmental performance and hotspot of NMs, based on LCA methodology. Therefore, this paper highlights and discusses LCA methodology’s basis (goal and scope definition, system boundary, life cycle inventory, life cycle impact assessment, and interpretation) to insights into current practices, limitations, progress, and challenges of LCA application NMs. We found that there is still a lack of comprehensive LCA study on the environmental impacts of NMs until end-of-life stages, thereby potentially supporting misleading conclusions, in most of the previous studies reviewed. For a comprehensive evaluation of LCA of NMs, we recommend that future studies should: (1) report more detailed and transparent LCI data within NMs LCA studies; (2) consider the environmental impacts and potential risks of NMs within their whole life cycle; (3) adopt a transparent and prudent characterization model; and (4) include toxicity, uncertainty, and sensitivity assessments to analyze the exposure pathways of NMs further. Future recommendations towards improvement and harmonization of methodological for future research directions were discussed and provided. This study’s findings redound to future research in the field of LCA NMs specifically, considering that the release of NMs into the environment is yet to be explored due to limited understanding of the mechanisms and pathways involved.

Physiological of biochar and α-Fe2O3 nanoparticles as amendments of Cd accumulation and toxicity toward muskmelon grown in pots

Background Due to the severe cadmium (Cd) pollution of farmland soil, effective measures need to be taken to reduce the Cd content in agricultural products. In this study, we added α-Fe2O3 nanoparticles (NPs) and biochar into Cd-contaminated soil to investigate physiological responses of muskmelon in the whole life cycle. Results The results showed that Cd caused adverse impacts on muskmelon (Cucumis melo) plants. For instance, the chlorophyll of muskmelon leaves in the Cd alone treatment was reduced by 8.07–32.34% in the four periods, relative to the control. The treatments with single amendment, α-Fe2O3 NPs or 1% biochar or 5% biochar, significantly reduced the soil available Cd content, but the co-exposure treatments (α-Fe2O3 NPs and biochar) had no impact on the soil available Cd content. All treatments could reduce the Cd content by 47.64–74.60% and increase the Fe content by 15.15–95.27% in fruits as compared to the Cd alone treatment. The KEGG enrichment results of different genes in different treatments indicated that single treatments could regulate genes related to anthocyanin biosynthesis, glutathione metabolism and MAPK signal transduction pathways to reduce the Cd toxicity. Conclusions Overall the combination of biochar and α-Fe2O3 NPs can alleviate Cd toxicity in muskmelon. The present study could provide new insights into Cd remediation in soil using α-Fe2O3 NPs and biochar as amendments. Graphic Abstract