Search

The use of a micro heat sink is an effective means of solving the problem of high-power chip heat dissipation. Diamond/Cu composites exhibit high thermal conductivity and a linear thermal expansion coefficient that is compatible with semiconductor materials, rendering them ideal micro heat sink materials. The aim of this study was to fabricate diamond/Cu and Cu separately as heat sinks and subject them to flow boiling heat transfer experiments. The results indicate that the diamond/Cu heat sink displayed a decrease in wall superheat of 10.2–14.5 °C and an improvement in heat transfer coefficient of 38–51% compared with the Cu heat sink under identical heat fluxes. The heat sink also exhibits enhanced thermal uniformity. Secondary diamond particles are incorporated into the gaps of the main diamonds, thereby constructing a three-dimensional heat conduction network within the composite material. The diamond network enhances the internal heat flux of the material while also creating more nucleation sites on the surface. These increase the boiling intensity of the diamond/Cu heat sink, leading to better heat transfer performance. By combining the transient thermal model with computational fluid dynamics, a heat transfer model based on the diamond/Cu heat sink is proposed. The efficient heat dissipation capability of diamond/Cu heat sinks can lower the working temperature of microelectronic devices, thereby improving device performance and reliability during operation. [ABSTRACT FROM AUTHOR]

• A new route choice principle for mixed traffic flow of autonomous vehicles and inertial human-driven vehicles. • Existence and uniqueness of the fixed point of the proposed day-to-day dynamic traffic assignment model. • Stability and convergence conditions for the proposed day-to-day dynamic traffic assignment model. Autonomous vehicle (AV) technology is likely to bring unprecedented change to existing transport systems due to its potential to enhance safety and efficiency. Nevertheless, before entering a fully AV era, human-driven vehicles (HVs) and AVs are expected to coexist for a long time, during which HVs and AVs could behave differently in route choice. On the one hand, compared with HVs, AVs can acquire more comprehensive traffic information and also process the information more swiftly. On the other hand, HV users may habitually maintain a satisfactory path but not necessarily choose the optimal one to the same destination to save cognitive during daily trips. AV users, however, may not show such behavior on account of the advantages of AVs. To capture these features in the coexistent period, understand their effects on the evolution of daily traffic flow, and provide managerial insights, this study presents a deterministic discrete time day-to-day dynamic assignment model for the mixed HV and AV traffic flows. In which both AV users and HV users choose their path according to their perception, AV users have better perceptual ability than HV users, and bounded behavioral inertia is first introduced to depict the travel behavior that HV users habitually maintain a satisfactory path during daily trips. The existence and uniqueness of the fixed-point and the convergence conditions of the proposed dynamic model are demonstrated and given. Theoretical results are verified in a simple two-path network, the Nguyen-Dupuis network, and the Sioux Falls network, respectively. The interactions between AVs and HVs are explored in the three numerical examples. Our research indicates that the introduction of AVs can reduce the overall travel time of a transport system and increase road capacity. Bounded behavioral inertia of HV users can maintain more HV flows on a better route, brings a more balanced distribution of travel flow on different paths, and facilitate the stability of a whole transport system. [ABSTRACT FROM AUTHOR]

A class of stochastic singular hybrid systems driven by both Brownian motion and Poisson jumps are studied. This paper is devoted to discussing the exponential stability and interval stability of such stochastic singular hybrid systems. The concept of interval admissibility is proposed. Sufficient conditions are given for exponential mean square admissibility and interval admissibility by using Itô’s formula, H -representation and spectrum technique. Finally, two simulation cases are presented to demonstrate the theoretical results. [ABSTRACT FROM AUTHOR]

This article explores the impact mechanism of different types of environmental regulations on corporate green technology innovation (GTI). The research focuses on analyzing three types of environmental regulations: command based environmental regulation (ER1), market-oriented environmental regulation (ER2), and voluntary environmental regulation (ER3), and how they affect corporate GTI. This study selected enterprise GTI as the dependent variable and measured it by the number of applications for green invention patents and green utility model patents. The independent variables are the three types of environmental regulations mentioned above. According to data from Chinese A-share listed companies. Using benchmark regression models to analyze the impact of different environmental regulations on GTI, and constructing a moderating effect model to study the role of corporate R&D investment and government support in the process of environmental regulations affecting GTI. The results indicate that (1) ER1, ER2, and ER3 can all promote enterprise GTI, and the three environmental regulatory methods have a better synergistic effect. (2) R&D investment has a positive correlation with the relationship between ER2 and GTI, and a negative correlation with ER 3 and ER 1. (3) There are differences in the GTI performance of enterprises in different regions, ownership nature, factor density, and industry types under the influence of environmental regulations. (4) The impact of environmental regulatory policies on corporate GTI is mainly short-term. This study provides a new perspective on how environmental regulations affect corporate GTI, especially in the context of developing countries like China. The research findings emphasize the role of different types of environmental regulations in incentivizing corporate GTI, while also pointing out factors that governments need to consider when formulating environmental policies, such as regional differences and corporate characteristics, which are of great significance for promoting green development of enterprises and achieving broader sustainable development goals. [ABSTRACT FROM AUTHOR]

The interface microzone characteristics determine the thermophysical properties of diamond/Cu composites, while the mechanisms of interface formation and heat transport still need to be revealed. Here, diamond/Cu-B composites with different boron content were prepared by vacuum pressure infiltration. Diamond/Cu-B composites up to 694 W/(mK) were obtained. The interfacial carbides formation process and the enhancement mechanisms of interfacial heat conduction in diamond/Cu-B composites were studied by HRTEM and first-principles calculations. It is demonstrated that boron can diffuse toward the interface region with an energy barrier of 0.87 eV, and these elements are energetically favorable to form the B4C phase. The calculation of the phonon spectrum proves that the B4C phonon spectrum is distributed in the range of the copper and diamond phonon spectrum. The overlapping of phonon spectra and the dentate structure together enhance the interface phononic transport efficiency, thereby improving the interface thermal conductance. [ABSTRACT FROM AUTHOR]

The fire-retardant synergy of tris(1-methoxy-2,2,6,6-tetramethyl-4-piperidinyl)-phosphite (NORPM) and melamine hydrobromide (MHB)/aluminum diethylphosphinate (ADEP) in polypropylene (PP) was characterized by UL-94 tests, limiting oxygen index (LOI) determination and cone calorimetry tests (CCT). NORPM exhibits an exceptional synergy in PP. The LOI and fire-retardant effectivity (EFF) of S-3 (the loadings of MHB and ADEP 1.00 and 1.50 wt%, respectively, no NORPM) were 19.0% and 0.48%, respectively, however, the LOI and EFF of S-15 (the loadings of NORPM, MHB and ADEP 0.2, 1.00 and 1.50 wt%, respectively) significantly increased to 25.5% and 2.85%, respectively, synergistic effectivity (SE) of NORPM is 2.03, and the fire-retardant rating was improved from none to UL 94 V-2 and the total heat release (THR) and peak heat release rate (PHRR) dropped obviously by adding the 0.2 wt% NORPM. The analysis by thermogravimetry-mass spectrum analysis (TG-MS) of the PP samples and the residues in the CCT revealed that NORPM, MHB and ADEP induced the synergy primarily by the following modes: CH3O·, aminyl radicals, CH3·and nitro radicals formed through the cracking of NORPM, along with the free radicals such as PO·, PO2· and HPO· pyrolyzed from ADEP and HBr from MHB, which quenched the active radicals, such as HO·, H·, ROO·, R· and broke down the radical source. The chain oxidation reaction of combustion was accordingly interrupted, which brought about the more exceptional fire-retardant effect than that of MHB/ADEP. [ABSTRACT FROM AUTHOR]

In this paper, a melamine formaldehyde resin modified with tris(2-hydroxyethyl) isocyanurate (THEIC), named MF-THEIC, was synthesized via a solid-phase reaction between hexahydroxymethyl melamine (HMM) and THEIC. MF-THEIC was firstly used as a charring agent in an intumescent flame-retardant system together with APP as well as 4A-zeolite in flame-retarding PP. APP/MF-THEIC (3/1) can effectively reinforce the flame retardancy of PP at a total 24.0 % additive amount, moreover, 1.5 % 4A-zeolite is sufficient to achieve an optimum synergistic effect. The corresponding composites (Sample-17) had passed UL-94 V-0 classification well. The synergistic flame-retarding mechanism was systematically investigated by SEM, 31P NMR, TGA, FTIR spectra, and TG-MS. 4A-zeolite can react with APP to generate highly-active phosphates with good catalytic efficacy on polyphosphate esterification, and then to promote the formation of the char layer, simultaneously, 4A-zeolite is helpful to enhance the char graphitization degree and the strength of the intumescing char layer, thereby reinforcing its flame retardancy via a synergistic effect. • A novel charring agent MF-THEIC was synthesized via a solid phase reaction between HMM and THEIC. • APP/MF-THEIC promoted the charring due to the chemical reactions. • 1.5 % 4A-zeolite synergistically improved the flame retardancy with APP/MF-THEIC in PP. • 4A-zeolite increased the graphitization degree and the strength of the intumescing char layer. [ABSTRACT FROM AUTHOR]

Bis(1-methoxy-2,2,6,6-tetramethylpiperidin-4-yl)sebacate (NORSM) was found to perform an exceptional synergistic effect with tris(2,4,6-tribromophenoxy)-1,3,5-triazine (TTBPC)/Sb2O3 in HIPS. The LOI of fire retardant HIPS (FR-HIPS) with 16 wt% of TTBPC/Sb2O3 increased from 23.8% to 25.2%, the flame retardant rating of FR-HIPS was improved from UL 94 V-2 to UL 94 V-0, and various heat release parameters such as peak heat release rate, total heat release, and mean effective heat of combustion were greatly lowered by combining NORSM of 0.50 wt%. The Py-GC/MS results revealed that NORSM induced the role of synergistic effect; the main mechanisms were as follows: the active radicals such as methoxy radicals and aminyl radicals produced by the pyrolysis of NORSM promote the release of bromine radicals from TTBPC and the formation of HBr and CO2, which improves the flame retardancy of TTBPC/Sb2O3; the above active radicals, together with HBr, quench active free radicals, such as the hydroxyl radical (OH), and decompose the free radical source, which interrupts the chain reaction during combustion and results in a more efficient flame retardant effect in gaseous phase. [ABSTRACT FROM AUTHOR]