Hasil untuk "Low temperature engineering. Cryogenic engineering. Refrigeration"

T. Kuehn, J. W. Ramsey, James L. Threlkeld

Rahul Davis, Gaurav Ninawe, Vishal Francis et al.

李睿, 刘斌, 胡恒祥 et al.

The increasing global warming and rapid growth of the ski industry have raised higher demands for artificial snowmaking technology and snow quality, with the quality of artificial snowmaking closely linked to the atomization characteristics of snowmaking nozzles.In this paper, the influence of different nozzle interference and gas-liquid mass mixing ratio (GLR) on droplet size distribution and collision mechanism in spray field is studied.The nozzle spacing (D) represents the degree of interference between nozzles, while the gas-liquid mass mixing ratio (GLR) signifies varying degrees of mixing disturbance under identical nozzles.The velocity and size distribution of droplets in the spray field were measured using a laser particle size measuring instrument and a high-speed camera, while the fragmentation and collision of droplets in the spray field were analyzed based on Weber number (We).The results indicate that the axial velocity of double nozzles exceeds that of single nozzles at varying spacing intervals. Specifically, when the nozzle spacing is 10 cm and 15 cm, the peak axial velocities are recorded as 5.6 m/s and 5.5 m/s respectively.The droplet size undergoes a non-monotonic variation with axial distance due to the competing effects of fragmentation and coalescence, initially decreasing before increasing.The interaction between the spray fields of two nozzles enhances droplet collision, resulting in a higher We number compared to that of individual nozzles. The analysis of the flow field of double nozzles under different arrangement conditions reveals that a higher level of uniformity in particle size distribution is observed when GLR=0.10 and D=15cm.

Xie Ruhe, Meng Xiangchao, Zou Yifeng et al.

With the development of cold chain Internet of Things (IoT) technology, real-time temperature monitoring and data sharing have become important means to improve the efficiency of chilled meat supply chain management. In this paper, a strategy for optimizing time and temperature coordination based on the cold chain IoT was proposed to improve the operational efficiency of the chilled meat supply chain. Based on predictive microbiology and system reliability theory, this study investigated the effects of time and temperature on the quality of chilled meat. A quality-change model for chilled meat and an energy consumption model for the chilled meat supply chain were developed. To illustrate this approach, a case study of a chilled chicken supply chain was conducted. The findings revealed that there is an optimal level of freshness in the chilled meat supply chain that maximizes the benefits of the supply chain. If the freshness level in one stage deviates from this optimal value, subsequent stages can adjust the time and temperature to achieve maximum supply chain efficiency.

Fahim Hafiz, Md Jahidul Hoq Emon, Md Abid Hossain et al.

This paper proposes a novel curriculum for the microprocessors and microcontrollers laboratory course. The proposed curriculum blends structured laboratory experiments with an open-ended project phase, addressing complex engineering problems and activities. Microprocessors and microcontrollers are ubiquitous in modern technology, driving applications across diverse fields. To prepare future engineers for Industry 4.0, effective educational approaches are crucial. The proposed lab enables students to perform hands-on experiments using advanced microprocessors and microcontrollers while leveraging their acquired knowledge by working in teams to tackle self-defined complex engineering problems that utilize these devices and sensors, often used in the industry. Furthermore, this curriculum fosters multidisciplinary learning and equips students with problem-solving skills that can be applied in real-world scenarios. With recent technological advancements, traditional microprocessors and microcontrollers curricula often fail to capture the complexity of real-world applications. This curriculum addresses this critical gap by incorporating insights from experts in both industry and academia. It trains students with the necessary skills and knowledge to thrive in this rapidly evolving technological landscape, preparing them for success upon graduation. The curriculum integrates project-based learning, where students define complex engineering problems for themselves. This approach actively engages students, fostering a deeper understanding and enhancing their learning capabilities. Statistical analysis shows that the proposed curriculum significantly improves student learning outcomes, particularly in their ability to formulate and solve complex engineering problems, as well as engage in complex engineering activities.

Bertrand Meyer

Software engineering concepts and processes are worthy of formal study; and yet we seldom formalize them. This "research ideas" article explores what a theory of software engineering could and should look like. Software engineering research has developed formal techniques of specification and verification as an application of mathematics to specify and verify systems addressing needs of various application domains. These domains usually do not include the domain of software engineering itself. It is, however, a rich domain with many processes and properties that cry for formalization and potential verification. This article outlines the structure of a possible theory of software engineering in the form of an object-oriented model, isolating abstractions corresponding to fundamental software concepts of project, milestone, code module, test and other staples of our field, and their mutual relationships. While the presentation is only a sketch of the full theory, it provides a set of guidelines for how a comprehensive and practical Theory of Software Engineering should (through an open-source community effort) be developed.

Xiaowen Tao, Yinuo Wang, Jinzhao Zhou

End-to-end reinforcement learning (RL) for motion control trains policies directly from sensor inputs to motor commands, enabling unified controllers for different robots and tasks. However, most existing methods are either blind (proprioception-only) or rely on fusion backbones with unfavorable compute-memory trade-offs. Recurrent controllers struggle with long-horizon credit assignment, and Transformer-based fusion incurs quadratic cost in token length, limiting temporal and spatial context. We present a vision-driven cross-modal RL framework built on SSD-Mamba2, a selective state-space backbone that applies state-space duality (SSD) to enable both recurrent and convolutional scanning with hardware-aware streaming and near-linear scaling. Proprioceptive states and exteroceptive observations (e.g., depth tokens) are encoded into compact tokens and fused by stacked SSD-Mamba2 layers. The selective state-space updates retain long-range dependencies with markedly lower latency and memory use than quadratic self-attention, enabling longer look-ahead, higher token resolution, and stable training under limited compute. Policies are trained end-to-end under curricula that randomize terrain and appearance and progressively increase scene complexity. A compact, state-centric reward balances task progress, energy efficiency, and safety. Across diverse motion-control scenarios, our approach consistently surpasses strong state-of-the-art baselines in return, safety (collisions and falls), and sample efficiency, while converging faster at the same compute budget. These results suggest that SSD-Mamba2 provides a practical fusion backbone for resource-constrained robotic and autonomous systems in engineering informatics applications.

Jin-peng Zhao, Zhongsheng Tan, Xiao-li Liu et al.

Nelly Bencomo, Jordi Cabot, Marsha Chechik et al.

Modern software-based systems operate under rapidly changing conditions and face ever-increasing uncertainty. In response, systems are increasingly adaptive and reliant on artificial-intelligence methods. In addition to the ubiquity of software with respect to users and application areas (e.g., transportation, smart grids, medicine, etc.), these high-impact software systems necessarily draw from many disciplines for foundational principles, domain expertise, and workflows. Recent progress with lowering the barrier to entry for coding has led to a broader community of developers, who are not necessarily software engineers. As such, the field of software engineering needs to adapt accordingly and offer new methods to systematically develop high-quality software systems by a broad range of experts and non-experts. This paper looks at these new challenges and proposes to address them through the lens of Abstraction. Abstraction is already used across many disciplines involved in software development -- from the time-honored classical deductive reasoning and formal modeling to the inductive reasoning employed by modern data science. The software engineering of the future requires Abstraction Engineering -- a systematic approach to abstraction across the inductive and deductive spaces. We discuss the foundations of Abstraction Engineering, identify key challenges, highlight the research questions that help address these challenges, and create a roadmap for future research.

S. C. C. Award, Marcel ter Brake

SAMUEL C. COLLINS AWARD 2023 Prof. Dr. Ir. H.J.M (Marcel) ter Brake University of Twente, Faculty of Science and Technology The Netherlands In 1965 the Cryogenic Engineering Conference (CEC) established an award in honor of the late Samuel C. Collins, Professor of Mechanical Engineering at the Massachusetts Institute of Technology. One of Professor Collins’ most notable works is his invention of the modern helium liquefier. The Collins Award is awarded to an individual who has made outstanding contributions to the identification and solution of cryogenic engineering problems and has additionally demonstrated a concern for the cryogenic community through service and leadership. The award is open to persons regardless of national origin. The CEC Awards Committee reviewed multiple nomination packages for highly qualified individuals and selected Marcel ter Brake as the recipient of the 2023 Samuel C. Collins Award. Marcel ter Brake received his PhD in 1986 at the University of Twente (UT) for his work on a SQUID-based horizontal-access rock magnetometer. Following his PhD, he became member of the Low Temperature Division at UT. Focus of his work was the realization of a Biomagnetic Center equipped with a magnetically shielded room and home-made multichannel SQUID-based neuromagnetometers. These magnetometers were all liquid-helium cooled. The advent of high-temperature superconductivity in 1986 allowed the use of small cryocoolers that were available on the market. The interfacing of these coolers to ultra-sensitive devices such as SQUIDs became an important field of ter Brake’s research. In this ongoing research, MEMS technologies were applied to fabricate cryocooler components. In addition to microcooling he also researched sorption-based compressors combined with Joule-Thomson coolers. These sorption coolers are essentially vibration free and are of interest specifically for optical instruments in scientific space missions but can also be beneficial in terrestrial applications. Marcel ter Brake was appointed Associate Professor at UT in 2000, and Full Professor and chair holder of Energy, Materials and Systems at UT since January 1st, 2010. Next to cryogenic technologies, this research chair investigates the use of superconductivity in high-current applications, focusing on systems to be applied in future energy chains. Marcel’s recent work is on ejectors to achieve lower temperatures and higher system efficiency in JT coolers. His work on the fundamental understanding of counter flow heat exchangers (CFHXs) and the associated mechanisms of flow maldistribution for two-phase flow in JT microcoolers. He has done excellent work on the heat-triggered switching of two-phase flow maldistribution in the heat exchanger of JT microcoolers by using both microscopic and temperature measurements that led to solutions to the challenge. Marcel ter Brake had a 10% Professor appointment at the Technological University of Eindhoven (TUE) from September 2004 to September 2010. He founded the Cryogenics Society of Europe in 2015 and until present he chairs the Board of that Society. Furthermore, he is lifetime member of the Cryogenic Society of America, chairs the International Cryogenic Engineering Committee and is board member of the International Cryocooler Conference. He has supervised and (co)-promoted 19 PhD students, has published more than 200 papers, of which 115 in refereed journals, and written 5 book chapters. Based on Marcel ter Brake’s impact in terms of technical achievement, leadership, and service to the cryogenics community, in the opinion of the awards committee, Marcel is a perfect example of what the Sam Collins Award is meant to recognize. THE RUSSELL B. SCOTT MEMORIAL AWARDS The Russell B. Scott Memorial Awards honor the first head of the Cryogenic Engineering Laboratory of the Boulder Laboratories of the National Bureau of Standards, now the National Institute of Standards and Technology. Mr. Scott was the founder of the Cryogenic Engineering Conference (CEC), the first of which was held in 1954 in Boulder, Colorado. He is the author of the book Cryogenic Engineering, published by the Princeton press in 1959. Mr. Scott retired in 1965 after 37 years at NBS and died in 1967. The Scott Memorial Awards provide an incentive for the production and presentation of high-quality papers at the Cryogenic Engineering Conferences, and recognition of authors who, in the judgment of the CEC Board of Directors, presented the best papers at the proceeding conference. The papers are nominated by the reviewers and editors of the conference proceedings. In 2023, two awards for the best papers delivered at the 2021 CEC Virtual Conference, and published in the IOP Conference Series: Materials Science and Engineering, Vol. 1240, 2022, were presented at the 2023 Honolulu conference to the following: Best Paper for Cryogenic Engineering Research A Anand, A S Gour, T S Datta and V V Rao for their paper “50 kJ SMES magnet design optimization using real coded genetic algorithm” IOP Conference Series: Materials Science and Engineering, Vol. 1240, 2022; 012137 Best Paper for Cryogenic Engineering Applications I Wells, J Bussey, N Swets, L Reising, C Butikofer, G Wallace, S Kulsa and J Leachman for their paper “Liquid nitrogen removal of lunar regolith simulant from spacesuit simulants” IOP Conference Series: Materials Science and Engineering, Vol. 1240, 2022; 012003

Fang Luo, Xiao-song Jiang, Hongliang Sun et al.

Molybdenum/tungsten–copper matrix composites are widely used in electronic engineering, aerospace, and other fields because of their excellent properties such as high hardness, high mechanical strength, low electrical and thermal conductivity, adjustable thermal expansion coefficient, and good high‐temperature stability. The densification, mechanical properties, and thermal properties are attributed to additive alloying elements, grain size and structure, and sintering parameters. Nevertheless, there are still some problems with densifying the composites due to the chemical incompatibility of molybdenum/tungsten and copper, and therefore the densification and strengthening mechanisms are reviewed to further improve densification and properties. Currently, the factors affecting thermal performance are scattered. Herein, the factors affecting the thermal conductivity of molybdenum/tungsten–copper matrix composites are reviewed, which provides a reference for the comprehensive performance optimization of molybdenum/tungsten–copper matrix composites. The future structure and simulation of molybdenum/tungsten–copper composites are also prospected. It provides a new way to improve the properties and structure of chemically incompatible metal composites.

A. Tanveer, Sharak Jarral

This paper emphasized an inclined magnetohydrodynamics (MHD) effects in tapered asymmetric porous channel with peristalsis in the presence of slip boundary conditions. Here we considered the two-dimensional channel with a porous medium. The fundamental assumptions of long wavelength and low Reynolds number are applied in the relevant nonlinear equations for momentum, heat, and mass transfer as part of mathematical modeling. The equations subjected to slip boundary conditions have been solved numerically by the Mathematica software. Various essential physical characteristics of velocity, temperature, concentration, and heat transfer rate are captured graphically in the end. The velocity profile is found parabolic for various involved parameters. It is observed that the embedded parameters behave in the exact opposite manner when compared with temperature and concentration distributions. The sinusoidal behavior of the heat transfer rate is also displayed. The unique aspect of this effort is specifically to relate the Joule heating, Darcy resistance, and inclined magnetic field effects in peristaltic flow for a non-Newtonian Jeffrey fluid in an asymmetric tapered channel under the influence of slip boundary conditions. Such preferences have a wide range of applications in engineering, biology, and industry. The outcomes of the presented work are also proficient in the medical field for the treatment of cancer using MHD. The MHD also aids in controlling blood pressure during systolic and diastolic pressure conditions by regulating the blood flow stream.

Hu Bin, Jiang Jiatong, Wu Di et al.

Currently, China's energy consumption is heavily reliant on coal, which is difficult to replace. The development of non-fossil fuels faces multiple constraints, and the industry is adversely affected by the issues of high energy consumption, high emissions, and low energy efficiency. Therefore, innovative low-carbon technologies urgently require further development. Heating accounts for half of all energy consumption; therefore, low-carbon heating is important for achieving carbon neutrality. To meet the capacity and temperature requirements of industrial heating, high-temperature water/steam heat pumps must be developed. This paper presents an analysis of the current status of industrial heat pump technology, including system cycles, refrigerant compression technology, and steam compression technology. Based on the development status of fourth-generation low-global warming potential refrigerants, the corresponding heat pump technologies should be well developed. Furthermore, industrial heat pump development prospects are discussed based on the development status and applications. Finally, application scenarios are predicted based on the market capacity and carbon reduction potentials.

Michael Dorner, Maximilian Capraro, Oliver Treidler et al.

The engineering of complex software systems is often the result of a highly collaborative effort. However, collaboration within a multinational enterprise has an overlooked legal implication when developers collaborate across national borders: It is taxable. In this article, we discuss the unsolved problem of taxing collaborative software engineering across borders. We (1) introduce the reader to the basic principle of international taxation, (2) identify three main challenges for taxing collaborative software engineering making it a software engineering problem, and (3) estimate the industrial significance of cross-border collaboration in modern software engineering by measuring cross-border code reviews at a multinational software company.

V. K. Narla, D. Tripathi, O. Bég

Abstract Biomimetic designs are increasingly filtering into new areas of technology in recent years. Such systems exploit characteristics intrinsic to nature to achieve enhanced adaptivity and efficiency in engineering applications. Peristaltic propulsion is an example of such characteristics and in the current article it is explored as a feasible mechanism for deployment in electrokinetic pumping of nanofluids through a curved distensible conduit as a model for a bioinspired smart device. The unsteady mass, momentum, energy and nanoparticle concentration conservation equations for a Newtonian aqueous ionic fluid under an axial electrical field are formulated and simplified using lubrication approximations and low zeta potential (Debye Huckel linearization). A dilute nanofluid is assumed with Brownian motion and thermophoretic body forces present. The reduced non-dimensional conservation equations are solved with the symbolic software, Mathematica 9 via the NDSolve algorithm for velocity, temperature, nano-particle concentration distributions for low zeta potential. An entropy generation analysis is also conducted. The influence of curvature parameter, maximum electroosmotic velocity (Helmholtz-Smoluchowski velocity), inverse EDL thickness parameter, zeta potential ratio and Joule heating parameter on transport characteristics is evaluated with the aid of graphs and contour plots. Temperature profiles are elevated with positive Joule heating and reduced with negative Joule heating whereas the opposite behaviour is observed for the nano-particle concentrations.

Trokon Cooper Herring, J. Thuo, Thimothy Nyomboi

Making low-cost concrete from coconut shell ash and coconut shell aggregate increases sustainability and reduces pollution. This research investigates untreated Coconut Shell Particles (CSP) incorporated with coconut shell ash (CSA) to improve the durability properties at elevated temperatures and in sulphuric acid. Initially, the physical and mechanical properties of cube and cylinder specimens after 7, 28, 56, and 90 days of moist curing were studied. The durability properties were then carried out after the pozzolanic component of CSA in modified concrete was activated. CSA and CSP were used as partial substitutes for ordinary Portland cement and coarse aggregate in class 30 concrete with a constant water to cement ratio of 0.55. Concrete mixes included control, 5% CSP, 10% CSA, and a mixture of 5% CSP incorporated with 10% CSA. According to test results, adding 10% of CSA to CSP concrete decreased the workability, density, and water absorption properties compared to the rest of the concrete mixes. However, these results were within acceptable limits. The compressive strength of 10% CSA concrete at 90 days of moist curing was reduced by 3.23% when 5% CSP was added compared to control. The addition of 10% of CSA to 5% CSP concrete improved the split tensile strength by 2.76% higher than concrete with only 5% CSP. Concrete containing the combination of 10% CSA and 5% CSP showed a 9.37% increment in the split tensile strength compared to concrete having only 5% CSP after sulphuric acid exposure. Also, the compressive strength of 10% CSA and 5% CSP concrete improved by 30.7% when the temperature was elevated to 500 °C for 1 hour compared to the control concrete. Moreover, the reduction in the compressive strength after exposure to the elevated temperature of 500 °C for 1 hr. was still much less by an average of 75.38% compared to other waste materials blended into the concrete by previous works. Doi: 10.28991/CEJ-2022-08-02-013 Full Text: PDF

K. Sun, Annan Zhou

Chen Youliang, Sheng Wei, Wang Ruirui et al.

Composite phase-change cold thermal energy storage materials have attracted significant attention in recent years; however, studies on their microscopic phase-change mechanism have garnered insignificant interest. In this study, the ice-water system with a high latent heat was mixed with polyethylene glycol (PEG) of mass fractions of 0%, 3%, and 5%, and using 10% glycerol and 20% ammonium chloride as the nucleating and cooling agents, respectively. The molecular dynamics method was used to simulate the phase transition process. The phase transition temperature was predicted and analyzed based on parameters such as the bonding and conformation, bond length, bond angle, radial distribution function, diffusion coefficient, and density. The results demonstrate that the lower the temperature, the lower the molecular kinetic energy, the smoother the molecular motion, and the greater the probability that the hydroxyl bond length will decrease. The temperature had a slight effect on the bond angle but a great impact on the bond length. With regard to the phase change, as the temperature decreased, the diffusion coefficient of the solution system decreased; the density increased; the solution viscosity increased; the orderliness increased. In the 10% glycerol-20% ammonium chloride aqueous system, the inflection point of the phase transition temperature was 255.2–256 K, which is very close to the experimental result of 255.5 K. After adding 3% and 5% PEG polymers, the phase transition temperature of the solution system was predicted to be 254.1–254.3 K and 253.5–253.8 K, demonstrating a decrease of 1.1–1.7 K and 1.7–2.2 K, respectively.

A. B. Mishra, Ruchi Karjodkar

Air India, the prestige of Tatas has the history dates to 1930s. The Air India was founded about 90 years ago as Tata Airlines and first ride was taken by the founder himself, J. R. D. Tata from Karachi to Bombay. The journey of Air India is an emotional rather than commercial. The Air India was nationalized by Government of India decades ago, but its progress under national entity is limited only for few decades. When the private carriers came into the field, and because of maintenance with respect to operations and human resource, the Air India was treated to be not only a company with loss, but also as a burdened national entity. In the process of disinvestment by Government of India, the Air India has arrived back at the Tata’s group. In this paper, a case study of Air India was presented covering all major milestones and inferences are presented.

Tan Jia, Guo Yingying, Zhou Xinli

Cryopreservation of testicular tissue is a potentially effective method to preserve fertility in infertile patients who cannot obtain sperm or prepubertal boys who have cancer and require radiotherapy or chemotherapy. In this study, the vitrification of massive mouse testicular tissue was studied. Massive testicular tissue was immersed in vitrification solutions with different concentrations for different immersion time. Thermal analysis was conducted using a differential scanning calorimeter, and the testicular tissue was vitrified. The results showed that ice crystals were formed in the tissue during the cooling process in the low-concentration CPA group. In contrast, vitrification was achieved during the cooling process in the high-concentration CPA group. According to the negative rate of apoptosis of spermatogenic cells, the optimal vitrification loading protocol was to incubate in 20% DMSO for 1 min, followed by incubation with spermatogonial cells 78.6%, spermatoblast cells 90%, sperm cells 70.1%, and Sertoli cells 89.1%. Compared to slow freezing with vitrification, slow freezing can maintain the morphological integrity of testicular tissue and reduce the apoptotic rate of spermatogenic cells, making it more suitable for freezing massive testicular tissue.