A numerical simulation method is used to investigate the flow and heat-transfer enhancement characteristics of a dimple-enhanced data center air-handling unit heat exchanger with Reynolds numbers ranging from 5 728 to 11 176. Traditional spherical dimples and three novel dimple types （ellipsoid， rounded stick， and rounded trapezoid） are studied. The results indicate that the traditional spherical dimple has poor heat-transfer enhancement performance， as its highest performance-evaluation criterion （PEC） is 1.067 （spherical dimple R15h2 with <italic>Re</italic> = 8 383）. Compared with the spherical-dimple channel， the high-velocity regions are all closer to the wall for the three novel dimple channels， which creates a thinner boundary layer that enhances heat transfer. Among the three novel dimple channels， the heat-transfer ability of the rounded-stick dimple channel is better than that of the ellipsoid dimple channel because of the larger high-velocity area near the upper wall of the channel and the fluid-impingement effect. The more complex second-flow vortexes result in a higher heat-transfer ability for the rounded trapezoid dimple channel compared with the rounded stick dimple. Under the same pumping power， the rounded trapezoid dimple channel can enhance the heat transfer by up to 33% compared with a flat-plate channel when <italic>Re</italic> = 5 728. In addition， the PEC of the rounded trapezoid dimple channel is larger than 1.27 in the tested Re region.
Heating and ventilation. Air conditioning, Low temperature engineering. Cryogenic engineering. Refrigeration
We present a vector network analyzer (VNA) based broadband cryogenic ferromagnetic resonance (FMR) spectrometer, operating up to 20 GHz over a temperature range of 11 to 350 K. A cost effective architecture is implemented through the integration of a closed cycle refrigerator (CCR) and a custom fabricated grounded coplanar waveguide (GCPW), designed for broadband transmission and reliable cryogenic operation. The VNA calibration is performed prior to measurements to account for microwave background and transmission losses, enabling reliable extraction of FMR spectra across the full temperature / frequency range. The sensitivity of the spectrometer is benchmarked using a yttrium iron garnet (YIG) thin film, yielding well resolved resonances with narrow linewidths and high sensitivity.
Ovarian tissue cryopreservation is an important method for female fertility preservation. Slow freezing of ovarian tissue results in poor follicular survival and low retransplantation efficiency. This study optimized the ovarian tissue cooling procedure by ice seeding, and the effects of ice seeding temperature and cooling rate after seeding on ovarian tissue cryopreservation were analyzed. The programmed cooling apparatus was combined with an ultrasonic device to achieve the ultrasonic seeding of ice crystals, and the ultrasonic intensity was screened. The ovarian survival and histology were assessed after rewarming. The results revealed that the optimized cooling procedure with ice seeding reduced the damage to ovarian tissues. When ice seeding was triggered at -11 ℃ with a cooling rate of 1 ℃/min after nucleation, follicle survival was 88.02%. Ultrasonic nucleation equipment enabled contactless ice seeding of the samples, reducing the risk of contamination and improving the success rate of ice seeding. Furthermore, the follicle survival rate of frozen ovarian tissue increased to 88.38%. The optimization of the procedure and the improvement of the equipment improved the effect of ovarian tissue cryopreservation, reduced the risk of introducing contamination during the cryopreservation process, and provided a new method for the slow cryopreservation of ovarian tissues in clinics.
Heating and ventilation. Air conditioning, Low temperature engineering. Cryogenic engineering. Refrigeration
Ovarian tissue cryopreservation is an important method of female fertility preservation, slow freezing of ovarian tissue has poor follicular survival and low retransplantation efficency. In this paper, the ovarian tissue cooling procedure was optimized by ice seeding, and the effects of ice seeding temperature and cooling rate after seeding on the ovarian tissue cryopreservation effect were analyzed. The programmed cooling apparatus was combined with an ultrasonic device to achieve ultrasonic seeding of ice crystals, and ultrasonic intensity was screened. Ovarian survival and histology were assessed after rewarming. The results showed that the optimized cooling procedure with ice seeding reduced the damage to ovarian tissues。When ice seeding was triggered at -11°C with a cooling rate of 1°C/min after nucleation, follicle survival was 88.02%. Ultrasonic nucleation equipment allowed contactless ice seeding of the samples, which reduced the risk of contamination and improved the success rate of ice seeding, and the follicle survival rate of frozen ovarian tissue increased to 88.38%. The optimization of the procedure as well as the improvement of the equipment improved the effect of ovarian tissue cryopreservation, reduced the risk of introducing contamination during the cryopreservation process, and provided a new method for the slow cryopreservation of ovarian tissues in the clinic.
Heating and ventilation. Air conditioning, Low temperature engineering. Cryogenic engineering. Refrigeration
The Full Flow Purifier for Fermilab's Muon Campus uses a charcoal bed surrounded by a liquid nitrogen jacket to purify up to 240 g/s of helium gas. Fabrication by Ability Engineering Technology Inc. has been completed and the purifier delivered to Fermilab. It is the largest purifier to be used at Fermilab based on both capacity and size. A previous paper discussed the design of purifier for various operational conditions and horizontal shipping. The purifier is designed to withstand 5g force in vertical and 2g force in lateral and longitudinal directions. Transportation experience from vendor to Fermilab and within site is discussed. Integration of the purifier involved design and fabrication of a liquid nitrogen transfer line, regeneration system, and helium piping to connect it to Muon Campus cryogenic system. It also involved establishing electrical, instrumentation and controls connections to the system. Integration of the purifier is discussed in detail. The purifier is to be commissioned using up to 4 MYCOM helium compressors to supply helium and liquid nitrogen supplied by a 60,000-liter tank. Actual effectiveness of the 3-stream heat exchanger is to be estimated based on measured temperatures and flow rate. Impurity levels will be monitored at inlet and outlet of the purifier. Theoretical adsorption capacity of the purifier is calculated based on the measured temperatures and flowrates and is compared to actual adsorption capacity over time.
The adoption of Building Information Modeling (BIM) and model-based design within the Architecture, Engineering, and Construction (AEC) industry has been hindered by the perception that using BIM authoring tools demands more effort than conventional 2D drafting. To enhance design efficiency, this paper proposes a BIM command recommendation framework that predicts the optimal next actions in real-time based on users' historical interactions. We propose a comprehensive filtering and enhancement method for large-scale raw BIM log data and introduce a novel command recommendation model. Our model builds upon the state-of-the-art Transformer backbones originally developed for large language models (LLMs), incorporating a custom feature fusion module, dedicated loss function, and targeted learning strategy. In a case study, the proposed method is applied to over 32 billion rows of real-world log data collected globally from the BIM authoring software Vectorworks. Experimental results demonstrate that our method can learn universal and generalizable modeling patterns from anonymous user interaction sequences across different countries, disciplines, and projects. When generating recommendations for the next command, our approach achieves a Recall@10 of approximately 84%. The code is available at: https://github.com/dcy0577/BIM-Command-Recommendation.git
Stuart M. Allen, Neil Chue Hong, Stephan Druskat
et al.
Research Software Engineering (RSEng) is a key success factor in producing high-quality research software, which in turn enables and improves research outcomes. However, as a principal investigator or leader of a research group you may not know what RSEng is, where to get started with it, or how to use it to maximize its benefit for your research. RSEng also often comes with technical complexity, and therefore reduced accessibility to some researchers. The ten simple rules presented in this paper aim to improve the accessibility of RSEng, and provide practical and actionable advice to PIs and leaders for integrating RSEng into their research group. By following these rules, readers can improve the quality, reproducibility, and trustworthiness of their research software, ultimately leading to better, more reproducible and more trustworthy research outcomes.
This short paper explores how a maritime company develops and integrates large-language models (LLM). Specifically by looking at the requirements engineering for Retrieval Augmented Generation (RAG) systems in expert settings. Through a case study at a maritime service provider, we demonstrate how data scientists face a fundamental tension between user expectations of AI perfection and the correctness of the generated outputs. Our findings reveal that data scientists must identify context-specific "retrieval requirements" through iterative experimentation together with users because they are the ones who can determine correctness. We present an empirical process model describing how data scientists practically elicited these "retrieval requirements" and managed system limitations. This work advances software engineering knowledge by providing insights into the specialized requirements engineering processes for implementing RAG systems in complex domain-specific applications.
Chaos Engineering is a discipline which enhances software resilience by introducing faults to observe and improve system behavior intentionally. This paper presents a design proposal for a customized Chaos Engineering framework tailored for Softtech, a leading software development company serving the financial sector. It outlines foundational concepts and activities for introducing Chaos Engineering within Softtech, while considering financial sector regulations. Building on these principles, the framework aims to be iterative and scalable, enabling development teams to progressively improve their practices. The study addresses two primary questions: how Softtech's unique infrastructure, business priorities, and organizational context shape the customization of its Chaos Engineering framework and what key activities and components are necessary for creating an effective framework tailored to Softtech's needs.
Refrigerants exhibit different diffusion and distribution characteristics when they encounter obstacles after leaking into confined spaces. The influence of the thermophysical parameters of refrigerants on their diffusion and distribution after encountering obstacles thus needs to be analyzed to facilitate the prediction of flammable areas during the leakage of flammable refrigerant. In this study, R717, R290, R32, and R1234yf were selected. The diffusion and distribution characteristics of the refrigerants encountering high and low obstacles in a confined space were investigated, and the influence of the thermophysical parameters of the refrigerants on the diffusion process and flammable area were analyzed in detail. The results indicated different patterns of rigid collision when the refrigerants encountered a high obstacle after leakage. Refrigerant with lower densities diffused rapidly in the direction opposite to the leakage direction and gathered at the top of the space, whereas refrigerants with higher densities diffused along the surface of the obstacle to the ground. As the height of the measurement point decreased, the mass concentration of R717 decreased from 2.04% to 0.024%, and the mass concentration of R1234yf increased from 0.192% to 1.64%. The mass concentrations of R290 and R744 below the leakage hole were 0.92% and 1.27%, respectively. When the densities of the refrigerants were similar, the refrigerant with a higher viscosity had a higher mass concentration. The flammable area was primarily located above the high obstacle, and as the refrigerant leakage increased, the flammable area in the <italic>y</italic>-<italic>z</italic> section of the space gradually extended to the ground. When refrigerants encountered low obstacles after leakage, they accumulated below the leakage hole and gradually diffused to other low mass concentration areas of the space along the surface of the low obstacle. The distribution of refrigerants with lower densities was more uniform. As the densities of refrigerants increased, they accumulated significantly below the leakage hole. As the height of the measurement point decreased, the mass concentrations of R1234yf and R717 increased from 0.066% and 1% to 2.12% and 1.14%, respectively. The flammable area was mainly located in the corner surrounded by the low obstacle and the wall below the leakage hole. With an increase in refrigerant leakage, the flammable area extended to the ground along the surface of the obstacle.
Heating and ventilation. Air conditioning, Low temperature engineering. Cryogenic engineering. Refrigeration
The Continuous software engineering is a collaborative software development environment which offers the continues development and deployment of quality software project within short time. The Continuous software engineering practices are not yet mature enough, and the software organizations hesitate to adopt it. This study aims: (1) to explore the Continuous software engineering challenges by conducting systematic literature review (SLR) and to get the insight of industry experts via questionnaire survey study; (2) to prioritize the investigated challenges using fuzzy analytical hierarchy process (FAHP). The study findings provides the set of critical challenges faced by the software organizations while adopting Continuous software engineering and a prioritization based taxonomy of the Continuous software engineering challenges. The application of FAHP is novel in this research area as it assists in addressing the vagueness of practitioners concerning the influencing factors of Continuous software engineering. We believe that the finding of this study will serve as a body of knowledge for real world practitioners and researchers to revise and develop the new strategies for the successful implementation of Continuous software engineering practices in the software industry.
Eriks Klotins, Michael Unterkalmsteiner, Tony Gorschek
Context: Start-up companies have become an important supplier of innovation and software-intensive products. The flexibility and reactiveness of start-ups enables fast development and launch of innovative products. However, a majority of software start-up companies fail before achieving any success. Among other factors, poor software engineering could be a significant contributor to the challenges experienced by start-ups. However, the state-of-practice of software engineering in start-ups, as well as the utilization of state-of-the-art is largely an unexplored area. Objective: In this study we investigate how software engineering is applied in start-up context with a focus to identify key knowledge areas and opportunities for further research. Method: We perform a multi-vocal exploratory study of 88 start-up experience reports. We develop a custom taxonomy to categorize the reported software engineering practices and their interrelation with business aspects, and apply qualitative data analysis to explore influences and dependencies between the knowledge areas. Results: We identify the most frequently reported software engineering (requirements engineering, software design and quality) and business aspect (vision and strategy development) knowledge areas, and illustrate their relationships. We also present a summary of how relevant software engineering knowledge areas are implemented in start-ups and identify potentially useful practices for adoption in start-ups. Conclusions: The results enable a more focused research on engineering practices in start-ups. We conclude that most engineering challenges in start-ups stem from inadequacies in requirements engineering. Many promising practices to address specific engineering challenges exists, however more research on adaptation of established practices, and validation of new start-up specific practices is needed.
Saara Tenhunen, Tomi Männistö, Matti Luukkainen
et al.
Tertiary education institutions aim to prepare their computer science and software engineering students for working life. While much of the technical principles are covered in lower-level courses, team-based capstone projects are a common way to provide students with hands-on experience and teach soft skills. This paper explores the characteristics of software engineering capstone courses presented in the literature. The goal of this work is to understand the pros and cons of different approaches by synthesising the various aspects of software engineering capstone courses and related experiences. In a systematic literature review for 2007-2022, we identified 127 primary studies. These studies were analysed based on their presented course characteristics and the reported course outcomes. The characteristics were synthesised into a taxonomy consisting of duration, team sizes, client and project sources, project implementation, and student assessment. We found out that capstone courses generally last one semester and divide students into groups of 4-5 where they work on a project for a client. For a slight majority of courses, the clients are external to the course staff and students are often expected to produce a proof-of-concept level software product as the main end deliverable. The courses also offer versatile assessments for students throughout the project. This paper provides researchers and educators with a classification of characteristics of software engineering capstone courses based on previous research. We further synthesise insights on the reported outcomes of capstone courses. Our review study aims to help educators to identify various ways of organising capstones and effectively plan and deliver their own capstone courses. The characterisation also helps researchers to conduct further studies on software engineering capstones.
Abstract High throughput approaches have become increasingly prevalent in the interdisciplinary space of polymer chemistry and biomedical engineering for the screening of polymer structure and biological activity. However, the syntheses of bioconjugates at high monomer dilutions and in a high throughput format are still challenging as there are typically limited quantities of the biological substrates available and cumbersome procedures for catalyst removal. Chitin is one of the most abundant natural polymers derived from seafood waste. This has inspired us to modify chitin for fabricating catalyst support. In this contribution, nanofibrous chitin (NC) microspheres as the matrix were employed for surface conjugation of eosin Y-bound copolymers via activated ester-amine reaction to prepare NCPNIEY microspheres. These microspheres hold great prospects for enabling high throughput polymerizations that possess advantages of photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization such as low-energy input, ultralow catalyst dosages and spatiotemporal control over chain propagation. The robustness of the NCPNIEY microspheres mediated protocol was demonstrated in the well-structured polymer syntheses and protein-polymer bioconjugation alongside catalyst-recycling experiments in multi-well plates. Raising the temperature of the reaction mixture to 37 °C caused segregation of the NCPNIEY microspheres in a hydrophilic-to-hydrophobic transition, allowing for the rapid purification of the protein-polymer bioconjugates without compromising protein activity. This work provides a versatile approach and useful insights for bioconjugate manufacturing in a high throughput format owing to simplified purification and improved sustainability.
Fiber-reinforced composites have become the preferred material in the fields of aviation and aerospace because of their high-strength performance in unit weight. The composite components are manufactured by near net-shape and only require finishing operations to achieve final dimensional and assembly tolerances. Milling and grinding arise as the preferred choices because of their precision processing. Nevertheless, given their laminated, anisotropic, and heterogeneous nature, these materials are considered difficult-to-machine. As undesirable results and challenging breakthroughs, the surface damage and integrity of these materials is a research hotspot with important engineering significance. This review summarizes an up-to-date progress of the damage formation mechanisms and suppression strategies in milling and grinding for the fiber-reinforced composites reported in the literature. First, the formation mechanisms of milling damage, including delamination, burr, and tear, are analyzed. Second, the grinding mechanisms, covering material removal mechanism, thermal mechanical behavior, surface integrity, and damage, are discussed. Third, suppression strategies are reviewed systematically from the aspects of advanced cutting tools and technologies, including ultrasonic vibration-assisted machining, cryogenic cooling, minimum quantity lubrication (MQL), and tool optimization design. Ultrasonic vibration shows the greatest advantage of restraining machining force, which can be reduced by approximately 60% compared with conventional machining. Cryogenic cooling is the most effective method to reduce temperature with a maximum reduction of approximately 60%. MQL shows its advantages in terms of reducing friction coefficient, force, temperature, and tool wear. Finally, research gaps and future exploration directions are prospected, giving researchers opportunity to deepen specific aspects and explore new area for achieving high precision surface machining of fiber-reinforced composites.
Seeing the significant increase in the number of nuclear power plants, as well as models and modifications of nuclear reactors, it becomes important to find out/establish the advantages of certain plants. At the same time, designers face a number of questions for which optimal solutions have not yet been found. At nuclear plants, there is the largest turnover of financial funds and the smallest gain in economy brings huge profits, but one should not forget about reliability and costs during the plant construction. This is a complex problem that is solved at the design stage. Calculations of the reactor at the design stage make it possible to determine the main parameters of the active zone, temperature values, etc. Thermohydraulic calculation of the active zone of the reactor is one of the cornerstones in justifying the safe operation of the nuclear power plant. Calculations of coolant parameters and temperatures of fuel elements are carried out at all stages of designing and proving the safety of nuclear power plants. Twisted pipes and finned heat transfer surfaces are widely used in engineering to increase the effective heat transfer coefficient. In particular, longitudinal, transverse, and spiral edges are used for finning the shells of fuel elements of nuclear reactors and the outer surfaces of steam generator pipes. Finning not only increases the heat transfer surface on the side where the heat transfer coefficient has a low value, but also significantly affects the hydrodynamics of the flow, and thus affects this coefficient. It is obvious that the better the medium is mixed in the main flow and in the intercoral zone, the higher the heat transfer coefficient is. The most profitable forms of fuel elements shells finning are chevron and polyzonal finning, which are performed in the form of a multiturn spiral with a large step. The R-function theory turned out to be quite convenient for building mathematical models of finned shells of fuel elements with straight and helical plates, as well as for building the corresponding objects on a 3D printer. From a practical point of view, the relevance of the problem is also determined by the significant spread of twisted cylindrical bodies, twisted channels, coils in the energy, chemical, oil, gas, metallurgical industries and in heat engineering equipment. The flows that arise at this time make it possible to intensify the processes of heat and mass exchange and achieve savings in energy resources
Abstract There has been an increasing interest in designing new types of architected metallic cellular structures (metallic meta-structures) for various engineering applications, such as thermal management devices, due to the advancements in metallic additive manufacturing technologies. In this work, the microstructure and mechanical properties of as-built and heat-treated additively manufactured AlSi10Mg triply periodic minimal surface (TPMS) sheet-based Schoen's I-graph - Wrapped Package (IWP) cellular structures are studied. Tensile coupons of the base material and IWP cellular structures are fabricated using laser powder bed fusion 3D printing technique, and thermomechanical tests are carried out. Scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), micro-computed tomography (micro-CT), and optical microscopy were utilized to visualize the surface morphology, fracture surfaces of the tensile coupons, grain orientation maps, and internal morphology of the samples. Micro-CT and experimentally measured relative densities of the fabricated cellular structures were found to be less than designed mainly due to the lack of proper fusion of metallic powder on complex surfaces leading to voids, especially at low relative densities. As-built samples undergo compression tests at 25 °C and exhibited brittle fracture while heat-treated samples undergo compression tests at 25 °C and 150 °C and exhibit more ductile behavior which is attributed to the grain growth during heat treatment, which was determined through the study of the EBSD maps. The tensile strength of the base material decreases with the increase of testing temperature, which is associated with a significant increase in elongation at fracture.