Optimization and Numerical Simulation of Multi-layer Microchannel Heat Sink

AbstractThe configuration sizes of multi-layer microchannel heat sink is optimized in order to enhance the performance of the high flux chip, which is 556W/cm2. Taking the thermal resistance and the pressure drop as goal functions, a double-objective optimization model was proposed based on the thermal resistance network model. The opimized microchannel heat sink is numerically simulated by computational fluid dynamics (CFD) software. The number of microchannel in width n1 and that in height n2 are 24 and 2, the width of optimized optimized microchannel and fin are 196 and 50μm, respectively, and the corresponding total thermal resistance of the whole microchannel heat sink is 0.4025°C/W. The highest temperature is less than 98°C, which can satisfy the requirement of chip to temperature. The maximum temperature difference is 77.8673°C, and the transferred power of heat flux is 200W, so the total thermal resistance is 0.3893°C/W, which agrees well with the analysis result of thermal resistance network model

Study on the Cooling Capacity of Different Quenchant

AbstractHeat treatment is one method to improve mechanical properties of metal, but each heat treatment method has its advantages and disadvantages, therefore, different requirements regarding size, shape, and properties with respect to different heat treatment processes should be considered. The traditional liquid quenchant are clear water and quench oil. Gas quenching is a relatively new process with several important advantages, such as minimal environmental impact, clean products, and ability to control the cooling locally and temporally for best product properties. To meet the high cooling rates required for quenching, the cooling gas must flow at very high velocities, but still the cooling capacity of gas is weakness. In order to increase the cooling capacity of gas, the spray water is added during gas quenching. In this paper, the GCr15 steel is as the research object, the cooling capacity of clear water, quench oil, nitrogen and nitrogen-spray water are studied through comparison of temperature difference and cooling velocity of the specimen

Optimization of ultrasound-microwave synergistic extraction of prebiotic oligosaccharides from sweet potatoes (Ipomoea batatas L.)

peer-reviewedIn this study, efficient ultrasound–microwave-assisted extraction (UMAE) of prebiotic oligosaccharides from sweet potatoes (Ipomoea batatas L.) was investigated. Response surface methodology was used to optimize the extraction conditions: extraction time, ultrasonic power, and microwave power. The prebiotic effect of extracted oligosaccharides on Bifidobacterium adolescentis was also investigated. The results show that the processing conditions of UMAE for optimum the yields of prebiotic oligosaccharides from sweet potatoes (PPOS4 and PPOS5) and corresponding absorbance (OD) are 100 s extraction time, 300 W ultrasonic power, and 200 W microwave power. Under these conditions, the experimental yields of PPOS4 and PPOS5 and the corresponding OD were 1.472%, 5.476%, and 2.966, respectively, which match the predicted values well. Compared with the conventional hot-water extraction (HWE), microwave-assisted extraction (MAE), and ultrasound assisted extraction (UAE) methods, the UMAE procedure exhibited significantly high extraction efficiency (p < 0.05). Comparison of SEM images of tissues of the sweet potatoes after extractions indicate microfractures and disruption of cell walls in the potato tissues. These results confirm that UMAE has great potential and efficiency in the extraction of bioactive substances in the food and medicinal industries

The Role of AM Symbiosis in Plant Adaptation to Drought Stress

Symposium paper Part 1: Function and management of soil microorganisms in agro-ecosystems with special reference to arbuscular mycorrhizal fung

Effect of ultrasound on physicochemical properties of emulsion stabilized by fish myofibrillar protein and xanthan gum

peer-reviewedTo investigate the effects ultrasound (20 kHz, 150–600 W) on physicochemical properties of emulsion stabilized by myofibrillar protein (MP) and xanthan gum (XG), the emulsions were characterized by Fourier transform infrared (FT-IR) spectroscopy, ζ-potential, particle size, rheology, surface tension, and confocal laser scanning microscopy (CLSM). FT-IR spectra confirmed the complexation of MP and XG, and ultrasound did not change the functional groups in the complexes. The emulsion treated at 300 W showed the best stability, with the lowest particle size, the lowest surface tension (26.7 mNm−1) and the largest ζ-potential absolute value (25.4 mV), that were confirmed in the CLSM photos. Ultrasound reduced the apparent viscosity of the MP-XG emulsions, and the changes of particle size were manifested in flow properties. Generally, ultrasound was successfully applied to improve the physical stability of MP-XG emulsion, which could be used as a novel delivery system for functional material

TRANSOM: An Efficient Fault-Tolerant System for Training LLMs

Large language models (LLMs) with hundreds of billions or trillions of parameters, represented by chatGPT, have achieved profound impact on various fields. However, training LLMs with super-large-scale parameters requires large high-performance GPU clusters and long training periods lasting for months. Due to the inevitable hardware and software failures in large-scale clusters, maintaining uninterrupted and long-duration training is extremely challenging. As a result, A substantial amount of training time is devoted to task checkpoint saving and loading, task rescheduling and restart, and task manual anomaly checks, which greatly harms the overall training efficiency. To address these issues, we propose TRANSOM, a novel fault-tolerant LLM training system. In this work, we design three key subsystems: the training pipeline automatic fault tolerance and recovery mechanism named Transom Operator and Launcher (TOL), the training task multi-dimensional metric automatic anomaly detection system named Transom Eagle Eye (TEE), and the training checkpoint asynchronous access automatic fault tolerance and recovery technology named Transom Checkpoint Engine (TCE). Here, TOL manages the lifecycle of training tasks, while TEE is responsible for task monitoring and anomaly reporting. TEE detects training anomalies and reports them to TOL, who automatically enters the fault tolerance strategy to eliminate abnormal nodes and restart the training task. And the asynchronous checkpoint saving and loading functionality provided by TCE greatly shorten the fault tolerance overhead. The experimental results indicate that TRANSOM significantly enhances the efficiency of large-scale LLM training on clusters. Specifically, the pre-training time for GPT3-175B has been reduced by 28%, while checkpoint saving and loading performance have improved by a factor of 20.Comment: 14 pages, 9 figure

Effect of plant protein mixtures on the microstructure and rheological properties of myofibrillar protein gel derived from red sea bream (Pagrosomus major)

peer-reviewedIn this study, the influence of plant protein mixtures (soy protein isolate (SPI) + peanut protein isolate (PPI), SPI + rice protein isolate (RPI), and PPI + RPI) on the microstructure, rheological properties and molecular driving forces of myofibrillar protein (MP) gels was studied. SPI could form a gel with smoother and denser network, while the structures of PPI and RPI gels were rougher, which led to the network structures of SPI + PPI and SPI + RPI gels but the disrupted structure of PPI + RPI gel. However, the SPI + RPI and PPI + RPI gels with different microstructures exhibited larger gel strength compared to the RPI gel. After mixing MP with the mixture of SPI + PPI and SPI + RPI, the mixed gels became more compact, evener and smoother, while the mixture of PPI + RPI induced more pores to the MP gel. However, G′ values of these three kinds of mixed gels were similar and much larger than that of MP gel. In addition, the molecular driving forces involved in the mixed plant protein gels and mixed MP-plant protein gels were mainly hydrophobic interactions and disulfide bonds

An efficient privacy-preserving outsourced computation over public data

Ministry of Education, Singapore under its Academic Research Funding Tier

Server-aided revocable attribute-based encryption

National Research Foundation (NRF) Singapor

A unified construction of weightwise perfectly balanced Boolean functions

At Eurocrypt 2016, Méaux et al. presented FLIP, a new family of stream ciphers {that aimed to enhance the efficiency of homomorphic encryption frameworks. Motivated by FLIP, recent research has focused on the study of Boolean functions with good cryptographic properties when restricted to subsets of the space $\mathbb{F}_2^n$. If an $n$-variable Boolean function has the property of balancedness when restricted to each set of vectors with fixed Hamming weight between $1$ and $n-1$, it is a weightwise perfectly balanced (WPB) Boolean function. In the literature, a few algebraic constructions of WPB functions are known, in which there are some constructions that use iterative method based on functions with low degrees of 1, 2, or 4. In this paper, we generalize the iterative method and contribute a unified construction of WPB functions based on functions with algebraic degrees that can} be any power of 2. For any given positive integer $d$ not larger than $m$, we first provide a class of $2^m$-variable Boolean functions with a degree of $2^{d-1}$. Utilizing these functions, we then present a construction of $2^m$-variable WPB functions $g_{m;d}$. In particular, $g_{m;d}$ includes four former classes of WPB functions as special cases when $d=1,2,3,m$. When $d$ takes other integer values, $g_{m;d}$ has never appeared before. In addition, we prove the algebraic degree of the constructed WPB functions and compare the weightwise nonlinearity of WPB functions known so far in 8 and 16 variables