To describe a semiconductor wafer fabrication flow availably, a new modeling method of extended hybrid Petri nets （EHPNs） was proposed. To model the discrete part and continuous part of a complex photolithography pr...To describe a semiconductor wafer fabrication flow availably, a new modeling method of extended hybrid Petri nets （EHPNs） was proposed. To model the discrete part and continuous part of a complex photolithography process, hybrid Petri nets （HPNs） were introduced. To cope with the complexity of a photolithography process, object-oriented methods such as encapsulation and classifications were integrated with HPN models. EHPN definitions were presented on the basis of HPN models and object-oriented methods. Object-oriented hybrid Petri subnet models were developed for each typical physical object and an EHPN modeling procedure steps were structured. To demonstrate the feasibility and validity of the proposed modeling method, a real wafer photolithography case was used to illustrate the modeling procedure. dynamic modeling of a complex photolithography process effectively The modeling results indicate that the EHPNs can deal with the dynamic modeling of a complex photolithography process effectively.展开更多
Lightweight hybrid structures of Al MMCs and titanium alloy dissimilar materials have great prospect in the defence industry application. So, it is necessary to join Al MMCs with Ti metal to achieve this structural de...Lightweight hybrid structures of Al MMCs and titanium alloy dissimilar materials have great prospect in the defence industry application. So, it is necessary to join Al MMCs with Ti metal to achieve this structural design. In this work, in-situ Ti B_(2)/7050 composite and TA2 were firstly attempted to join by TIG welding-brazing technique. The result was that the intact welding-brazing butt joint was successfully fabricated. The joint presents dual characteristics, being a brazing on TA2 side and a welding on Ti B_(2)/7050 side. At brazing joint side, ER4043 filler metal effectively wets on TA2 under TIG heating condition,and a continuous interfacial reaction layer with 1 e3 mm is formed at welded metal/TA2 interface. The whole interfacial reaction layers are composed of Ti(Al Si)3 intermetallic compounds(IMCs), but their morphologies at the different regions present obvious distinguishes. The microhardness of the reaction layers is as much as 141 e190 HV. At welding joints side, the fusion zone appears the equixaed crystal structure, and the grain sizes are much smaller than those of welded metal, which is attributed to the effect of Ti B2 particulates from the melted Ti B_(2)/7050 on acceleration formation and inhibiting growth for the new crystal nucleus. The tensile test results show that average tensile strength of the optimal welding-brazing joint is able to achieve 138 MPa. The failure of the tensile joint occurs by quasi-cleavage pattern, and the cracks initiate from the IMCs layer at the groove surface of TA2 and propagate into the welded metal.展开更多
A simple and easily operated technique was developed to fabricate GaN films. GaN films possessing hexagonal wurtzite structure were fabricated on Si(111) substrates with ZnO buffer layers through nitriding Ga2O3 films...A simple and easily operated technique was developed to fabricate GaN films. GaN films possessing hexagonal wurtzite structure were fabricated on Si(111) substrates with ZnO buffer layers through nitriding Ga2O3 films in the tube quartz furnace. ZnO buffer layers and Ga3O3 films were deposited on Si substrates in turn by using radio frequency magnetron sputtering system before the nitriding process. The structure and composition of GaN films were studied by X-ray diffraction, selected area electron diffraction and Fourier transform infrared spectrophotometer. The morphologies of GaN films were studied by scanning electron microscopy. The results show that ZnO buffer layer improves the crystalline quality and the surface morphology of the films relative to the films grown directly on silicon substrates. The measurement result of room-temperature photoluminescence spectrum indicates that the photoluminescence peaks locate at 365 nm and 422 nm.展开更多
A typical contemporary computerized product develop me nt workflow is outlined in Fig.1. Product geometry information is first prep ared with computer-aided design (CAD) software. The CAD format can then be com munica...A typical contemporary computerized product develop me nt workflow is outlined in Fig.1. Product geometry information is first prep ared with computer-aided design (CAD) software. The CAD format can then be com municated to other downstream-computerized applications like, computer-aided e ngineering analysis (CAE), computer-aided manufacturing (CAM) and/or rapid prot otyping. Since design may need to be modified to incorporate new requirements, a loop back path is also depicted in Fig.1. The design engineers will check ac cording to their experience, result of physical test and CAE simulation to decid e whether redesign is needed or not. If the design passes all tests, its pr ototype or product can be produced. Otherwise, the current practice is to chang e its geometry and/or select a more appropriate material. The iteration repeat s until the latest version satisfies the engineering specification and customer requirements. Note that the material is homogeneous in the part to be designed. With the advent of functionally graded material (FGM) research, a new workflow will become possible. Components incorporating FGM’s can be designed to achieve levels of performance superior to that of homogeneous materials by combining the desirable properties of each constituent phase. Theoretically, the material composition can be tailo red within a component to achieve local control of properties; for example, form ability, corrosion resistance, hardness, toughness, and so on. By such local co ntrol, monolithic components can be created that integrate the function of multi ple discrete components, saving part count, space, weight, and enabling concepts that would otherwise be impractical. Controlling the spatial distribution of p roperties via composition will allow for control of the state of the entire comp onent (the state of residual stress in a component). There are various methods p roposed to produce FGM components. In particular, solid freeform fabrication ( SFF) methods are commonly used to directly fabricate an FGM part in an additive fashion directly from a computer controlled, layer-by-layer, additive process in which a standard CAD is sliced into a series of horizontal planes. Common SF F techniques being investigated include three-dimensional printing (3DP), Lamin ate Object Manufacturing (LOM), Extrusion Freeform Fabrication (EFF), Selective Laser Sintering (SLS) and even Stereolithography (SL). Fig.1 Current CAE design workflow Fig.2 Proposed CAE design workflow for FGM Albeit the feasibility to fabricate FGM components, one gap still needs to be fi lled for real life FGM product design; namely, where and how to grade the compon ent. This paper will, thus, address issues on incorporating FGM for design impr ovement. Rather than changing the geometry or reselecting a new material, a FGM approach can be employed in design enhancement as shown in Fig.2. The same geo metry and material is retained except that functional property in needed regions is selectively reinforced. As in conventional workflow, CAE simulation is perf ormed after CAD modelling. CAE simulation is preferred since physical test is v ery expensive and most of them are destructive. Moreover, the experience of the engineers may not be accurate. More importantly, the result of CAE simulation is used in this research to produce a stress intensity map for selective reinfor cement. The map will be converted to tool path control signals for generating FG component via SFF machine. On the implementation side, SolidWorks is used fo r CAD modeling, COSMOS/Works is used for CAE simulation. The model is then selec tively reinforced according to the simulation result to produce a FGM enriched p ath plan to drive the Z-corp machine. Case studies are performed to verify the approach. The preliminary result is positive. Future extension to material oth er than starch and plaster powders and enhancement other than stress distributio n may be explored. In conclusion, a CAE-based methodology for FGM product des ign展开更多
Rutile phase exhibits higher refractive index and h id ing power, good chemical stability, and is becoming a candidate material for the high-temperature separation and catalysis applications. The thermodynamically sta...Rutile phase exhibits higher refractive index and h id ing power, good chemical stability, and is becoming a candidate material for the high-temperature separation and catalysis applications. The thermodynamically stable feature of rutile among the three polymorphs of TiO 2 usually hinders ob taining nano-sized rutile phase by a conventional calcining way. However, acid peptization of amorphous TiO 2 is favorable to the formation of rutile phase. I n this work, well-crystallized and well-dispersed rod-like rutile particles w ith specific surface areas of 49.1 and 35.0 m 2/g were prepared by hydrothermal ly treating the acid peptized TiO 2 amorphous sols at relatively low temperatur es of 200 ℃ or 240 ℃, respectively. The formation of non-touching rutile part icles is attributed to high long-range electrostatic forces between particles i n the presence of the high concentration of the peptizer. The acid peptization w ould easily break the ≡Ti-O-Ti≡ bonds to form ≡Ti-OH or HO-Ti-OH species depending on the amount of acid, and create conditions for the formation of rut ile nuclei after structural rearrangements.展开更多
Cordierite is a promising low-k material in mi cr oelectronic and packaging industries. When it is co-fired with the metal for re alising the multilayer circuits, temperature should be low enough to prevent the meltin...Cordierite is a promising low-k material in mi cr oelectronic and packaging industries. When it is co-fired with the metal for re alising the multilayer circuits, temperature should be low enough to prevent the melting and/or oxidising of the metal. However, this temperature is usually too low to sinter cordierite. Low melting point glass, therefore, is added to the s toichiometric cordierite to lower the sintering temperature through a liquid-si ntering process. In this research work, cordierite-based glass ceramics tapes were prepared by t ape casting from suspensions containing different solids loading and different m ean particle sizes. The optimal experimental conditions for obtaining homogenous green tapes were determined by varying the type and concentration of dispersant s and binders, the solids loading as well as the particle sizes of both cordieri te and glass. Scanning electron microscopy (SEM) and Hg porosimetry were used to characterise the green tapes. The results showed that high values of solids vol ume fractions and of the size ratio between the mean particle sizes of glass and cordierite powders favour the obtaining of homogeneous and high dense substrate s. The dielectric constant of the sintered bodies at 1 100 ℃ was around 5 and t he dissipation factor was about 0.01 at 1 MHz.展开更多
Hyperledger Fabric是一个主流的联盟链平台,当面临多笔并发执行且相互关联的交易时,现有架构容易生成大量无效交易,这严重降低了系统的有效交易处理能力。为了解决这一问题,提出一种融合映射与有向无环图(DAG)的冲突消除机制—FabricIM...Hyperledger Fabric是一个主流的联盟链平台,当面临多笔并发执行且相互关联的交易时,现有架构容易生成大量无效交易,这严重降低了系统的有效交易处理能力。为了解决这一问题,提出一种融合映射与有向无环图(DAG)的冲突消除机制—FabricIMD(Fabric integrated with map and DAG)。该机制在背书节点处通过映射识别交易间依赖关系,并使用有向无环图对此关系进行构建,以调整交易背书顺序,从而有效避免了交易冲突现象的出现。实验证明,当存在多笔相互关联的并发交易时,FabricIMD机制能显著减少因交易冲突导致的无效交易。随着交易间冲突程度的变化,系统有效交易吞吐量提升了15.68%~96.08%。此外,在处理无关联的并发交易时,引入该机制并未对系统性能造成显著影响。综上,FabricIMD机制在避免交易冲突现象出现的同时提高了系统有效交易吞吐量,减少了无效交易数量。展开更多
Despite numerous research investigations to understand the influences of various structural parameters,to the authors'knowledge,no research has been the effect of different angles of incidence on stab response and...Despite numerous research investigations to understand the influences of various structural parameters,to the authors'knowledge,no research has been the effect of different angles of incidence on stab response and performance of different types of protective textiles.Three distinct structures of 3D woven textiles and 2D plain weave fabric made with similar high-performance fiber and areal density were designed and manufactured to be tested.Two samples,one composed of a single and the other of 4-panel layers,from each fabric type structure,were prepared,and tested against stabbing at[0○],[22.5○],and[45○]angle of incidence.A new stabbing experimental setup that entertained testing of the specimens at various angles of incidence was engineered and utilized.The stabbing bench is also equipped with magnetic sensors and a UK Home Office Scientific Development Branch(HOSDB)/P1/B sharpness engineered knives to measure the impact velocity and exerted impact energy respectively.A silicon compound was utilized to imprint the Back Face Signature(BFS)on the backing material after every specimen test.Each silicon print was then scanned,digitized,and precisely measured to evaluate the stab response and performance of the specimen based on different performance variables,including Depth of Trauma(DOT),Depth of Penetration(DOP),and Length of Penetration(LOP).Besides,the post-impact surface failure modes of the fabrics were also measured using Image software and analyzed at the microscale level.The results show stab angle of incidence greatly influences the stab response and performance of protective textiles.The outcome of the study could provide not only valuable insights into understanding the stab response and capabilities of protective textiles under different angle of incidence,but also provide valuable information for protective textile manufacturer,armor developer and stab testing and standardizing organizations to consider the angle of incidence while developing,testing,optimizing,and using protective textiles in various applications.展开更多
Aramid fibers,due to their relatively high inter-yarn friction,high strength,high modulus,and other characteristics,have become a typical representative of flexible anti-ballistic materials in modern warfare.Current r...Aramid fibers,due to their relatively high inter-yarn friction,high strength,high modulus,and other characteristics,have become a typical representative of flexible anti-ballistic materials in modern warfare.Current research on the anti-penetration of aramid fabrics mostly focuses unilaterally on the structure and performance of aramid fabrics or the shape and size of projectiles,with fewer studies on the coupled effect of both on ballistic performance.This study analyzes how the coupling relationship(or size effect)between the projectile and fiber bundle dimensions affects the fabric ballistic performance from a mesoscopic scale perspective.Taking plain weave aramid fabric as the research object,considering different diameter projectiles,through a large number of ballistic impact tests and numerical simulations,parameters such as ballistic limit velocity,average energy absorption of fabric,and specific energy absorption ratio(average energy absorption of fabric divided by projectile cross-sectional area)are obtained for ballistic performance analysis.The influence law of projectile size on the ballistic performance of high-performance fabrics is as follows:The relative range of fitted ballistic limit velocity at different target positions gradually decreases and then stabilizes as the projectile diameter increases,indicating that the fabric structure effect gradually disappears at a projectile diameter of 12 mm;The average ballistic limit velocity at three impact positions,P1,P2,and P3,provides the corresponding ballistic limit velocity for 1000D aramid fabric,which increases with projectile diameter but the rate of increase slows down at an inflection point,which in this study occurs where the fabric structure effect nearly disappears at a projectile diameter of 12 mm;The energy absorption ratio increases and then decreases as the projectile diameter increases from 4 mm to 20 mm,reaching a peak at the diameter of 12 mm due to the gradual disappearance of the fabric structural effect.The projectile diameter of 12 mm corresponds to the coupling size of 11.159,which provides a size design reference for the macroscopic-based continuum models of aramid plain weave fabrics.展开更多
Inspired by the thermal stability mechanism of thermophilic protein,which presents ionic bonds that have better stability at higher temperatures,this paper proposes the introduction of electrostatic interactions by ad...Inspired by the thermal stability mechanism of thermophilic protein,which presents ionic bonds that have better stability at higher temperatures,this paper proposes the introduction of electrostatic interactions by adding carboxyl-modified silica(C-SiO2),PAA,and CaCl_(2) to achieve higher viscosity over 25℃.The rheological behavior of C-SiO_(2)-based shear thickening fluid(CS-STF)was investigated at a temperature range of 25–55℃.Unlike SiO_(2)-based STF,which exhibits single-step thickening and a negative correlation between viscosity and temperature.As the C-SiO_(2) content was 41%(w/w)and the mass ratio of PAA:CaCl_(2):C-SiO_(2) was 3:1:10,the CS-STF displayed a double-thickening behavior,and the peak viscosity reached 1330 Pa·s at 35℃.From the yarn pull-out test,the inter-yarn force was significantly increased with the increasing CS-STF content.Treating UHMWPE fabrics with CS-STF improved the impact resistance effectively.In the blunt impact test,the U-CS fabrics with high CS-STF content(121.45 wt%)experienced penetration failure under high impact energy(18 J)due to stress concentration caused by the shear thickening behavior.The knife stabbing test demonstrated that U-CS fabrics with appropriate content(88.38 wt%)have the best stabbing resistance in various impact energies.Overall,this study proposed a high-performence STF showing double-thickening and enhancing shear-thickening behavior at a wide temperature range,the composite fabrics with the performance of resisting both the blunt and stab impact had broad application prospects in the field of personal protection.展开更多
Chemical warfare agents(CWAs)are extremely lethal substances used in warfare and terrorism,capable of causing permanent damage even in small doses,despite medical intervention.Therefore,detection,protection,and detoxi...Chemical warfare agents(CWAs)are extremely lethal substances used in warfare and terrorism,capable of causing permanent damage even in small doses,despite medical intervention.Therefore,detection,protection,and detoxification of CWAs are vital for the safety of first responders,military personnel,and civilians,driving significant research in this area.Herein,we designed and synthesized a poly(-diallyldimethylammonium chloride)(PDDA)mediated cupric oxide(CuO)functionalized activated carbon fabric(ACF),termed ACF@PDDA-CuO,as an adsorbent filter material for self-detoxifying chemical protective clothing.PDDA,a positively charged polyelectrolyte,effectively binds in-situ synthesized CuO to the negatively charged ACF surface,serving as a suitable binder.This study demonstrates the synergistic effects of PDDA-CuO functionalization on ACF,where PDDA treatment enhanced mechanical and comfort properties,and CuO crystal growth significantly improved detoxification efficacy against the CWA Nerve Agent Sarin.Comprehensive analyses,including FTIR,BET surface area analysis,SEM,EDS,TEM,STEM,TGA,XPS,and XRD,confirmed the uniform deposition of CuO and PDDA on the ACF surface.The Cu content on ACF@PDDA-CuO samples was measured via iodometric titration.The materials were evaluated for tensile strength,air permeability,water vapor permeability,nerve agent(Sarin)detoxification,and blister agent(Sulfur Mustard)breakthrough time to assess their applicability for protective clothing.The optimized PDDA-CuO on ACF detoxified 82.04%of Sarin within 18 h,compared to 25.22%by ACF alone,and enhanced tensile strength by 23.67%,air permeability by 24.63%,and water vapor permeability by 3.94%,while maintaining protection against Sulfur Mustard for 24 h.These findings indicate that ACF@PDDA-CuO is a promising candidate for CWA protective clothing,offering robust protection with enhanced comfort.展开更多
Stab-resistant textiles play a critical role in personal protection,necessitating a deeper understanding of how structural and layering factors influence their performance.The current study experimentally examines the...Stab-resistant textiles play a critical role in personal protection,necessitating a deeper understanding of how structural and layering factors influence their performance.The current study experimentally examines the effects of textile structure,layering,and ply orientation on the stab resistance of multi-layer textiles.Three 3D warp interlock(3DWI)structures({f1},{f2},{f3})and a 2D woven fabric({f4}),all made of high-performance p-aramid yarns,were engineered and manufactured.Multi-layer specimens were prepared and subjected to drop-weight stabbing tests following HOSBD standards.Stabbing performance metrics,including Depth of Trauma(DoT),Depth of Penetration(DoP),and trauma deformation(Ymax,Xmax),were investigated and analyzed.Statistical analyses(Two-and One-Way ANOVA)indicated that fabric type and layer number significantly impacted DoP(P<0.05),while ply orientation significantly affected DoP(P<0.05)but not DoT(P>0.05).Further detailed analysis revealed that 2D woven fabrics exhibited greater trauma deformation than 3D WIF structures.Increasing the number of layers reduced both DoP and DoT across all fabric structures,with f3 demonstrating the best performance in multi-layer configurations.Aligned ply orientations also enhanced stab resistance,underscoring the importance of alignment in dissipating impact energy.展开更多
随着区块链技术应用的普及,联盟链Hyperledger Fabric(简称Fabric)已成为知名区块链开源平台,并得到广泛关注.然而Fabric仍受困于并发事务间冲突问题,冲突发生时会引发大量无效交易上链,导致吞吐量下降,阻碍其发展.对于该问题,现有面向...随着区块链技术应用的普及,联盟链Hyperledger Fabric(简称Fabric)已成为知名区块链开源平台,并得到广泛关注.然而Fabric仍受困于并发事务间冲突问题,冲突发生时会引发大量无效交易上链,导致吞吐量下降,阻碍其发展.对于该问题,现有面向块内冲突的方案缺乏高效的冲突检测和避免方法,同时现有研究往往忽略区块间冲突对吞吐量的不利影响.提出了一种Fabric的优化方案Fabric-HT(fabric with high throughput),从区块内和区块间2方面入手,有效降低事务间并发冲突和提高系统吞吐量.针对区块内事务冲突,提出了一种事务调度机制,根据块内冲突事务集定义了一种高效数据结构——依赖关系链,识别具有“危险结构”的事务并提前中止,合理调度事务和消除冲突;针对区块间事务冲突,将冲突事务检测提前至排序节点完成,建立以“推送-匹配”为核心的冲突事务早期避免机制.在多场景下开展大量实验,结果表明Fabric-HT在吞吐量、事务中止率、事务平均执行时间、无效事务空间占用率等方面均优于对比方案.Fabric-HT吞吐量最高可达Fabric的9.51倍,是最新优化方案FabricSharp的1.18倍;空间利用率上相比FabricSharp提升了14%.此外,Fabric-HT也表现出较好的鲁棒性和抗攻击能力.展开更多
基金Project(60574054) supported by the National Natural Science Foundation of China
文摘To describe a semiconductor wafer fabrication flow availably, a new modeling method of extended hybrid Petri nets （EHPNs） was proposed. To model the discrete part and continuous part of a complex photolithography process, hybrid Petri nets （HPNs） were introduced. To cope with the complexity of a photolithography process, object-oriented methods such as encapsulation and classifications were integrated with HPN models. EHPN definitions were presented on the basis of HPN models and object-oriented methods. Object-oriented hybrid Petri subnet models were developed for each typical physical object and an EHPN modeling procedure steps were structured. To demonstrate the feasibility and validity of the proposed modeling method, a real wafer photolithography case was used to illustrate the modeling procedure. dynamic modeling of a complex photolithography process effectively The modeling results indicate that the EHPNs can deal with the dynamic modeling of a complex photolithography process effectively.
基金supported by Basic Science Research Project of Colleges and Universities in Liaoning Province in China (No. LG201714)。
文摘Lightweight hybrid structures of Al MMCs and titanium alloy dissimilar materials have great prospect in the defence industry application. So, it is necessary to join Al MMCs with Ti metal to achieve this structural design. In this work, in-situ Ti B_(2)/7050 composite and TA2 were firstly attempted to join by TIG welding-brazing technique. The result was that the intact welding-brazing butt joint was successfully fabricated. The joint presents dual characteristics, being a brazing on TA2 side and a welding on Ti B_(2)/7050 side. At brazing joint side, ER4043 filler metal effectively wets on TA2 under TIG heating condition,and a continuous interfacial reaction layer with 1 e3 mm is formed at welded metal/TA2 interface. The whole interfacial reaction layers are composed of Ti(Al Si)3 intermetallic compounds(IMCs), but their morphologies at the different regions present obvious distinguishes. The microhardness of the reaction layers is as much as 141 e190 HV. At welding joints side, the fusion zone appears the equixaed crystal structure, and the grain sizes are much smaller than those of welded metal, which is attributed to the effect of Ti B2 particulates from the melted Ti B_(2)/7050 on acceleration formation and inhibiting growth for the new crystal nucleus. The tensile test results show that average tensile strength of the optimal welding-brazing joint is able to achieve 138 MPa. The failure of the tensile joint occurs by quasi-cleavage pattern, and the cracks initiate from the IMCs layer at the groove surface of TA2 and propagate into the welded metal.
基金Projects(90301002 90201025) supported by the National Natural Science Foundation of China
文摘A simple and easily operated technique was developed to fabricate GaN films. GaN films possessing hexagonal wurtzite structure were fabricated on Si(111) substrates with ZnO buffer layers through nitriding Ga2O3 films in the tube quartz furnace. ZnO buffer layers and Ga3O3 films were deposited on Si substrates in turn by using radio frequency magnetron sputtering system before the nitriding process. The structure and composition of GaN films were studied by X-ray diffraction, selected area electron diffraction and Fourier transform infrared spectrophotometer. The morphologies of GaN films were studied by scanning electron microscopy. The results show that ZnO buffer layer improves the crystalline quality and the surface morphology of the films relative to the films grown directly on silicon substrates. The measurement result of room-temperature photoluminescence spectrum indicates that the photoluminescence peaks locate at 365 nm and 422 nm.
文摘A typical contemporary computerized product develop me nt workflow is outlined in Fig.1. Product geometry information is first prep ared with computer-aided design (CAD) software. The CAD format can then be com municated to other downstream-computerized applications like, computer-aided e ngineering analysis (CAE), computer-aided manufacturing (CAM) and/or rapid prot otyping. Since design may need to be modified to incorporate new requirements, a loop back path is also depicted in Fig.1. The design engineers will check ac cording to their experience, result of physical test and CAE simulation to decid e whether redesign is needed or not. If the design passes all tests, its pr ototype or product can be produced. Otherwise, the current practice is to chang e its geometry and/or select a more appropriate material. The iteration repeat s until the latest version satisfies the engineering specification and customer requirements. Note that the material is homogeneous in the part to be designed. With the advent of functionally graded material (FGM) research, a new workflow will become possible. Components incorporating FGM’s can be designed to achieve levels of performance superior to that of homogeneous materials by combining the desirable properties of each constituent phase. Theoretically, the material composition can be tailo red within a component to achieve local control of properties; for example, form ability, corrosion resistance, hardness, toughness, and so on. By such local co ntrol, monolithic components can be created that integrate the function of multi ple discrete components, saving part count, space, weight, and enabling concepts that would otherwise be impractical. Controlling the spatial distribution of p roperties via composition will allow for control of the state of the entire comp onent (the state of residual stress in a component). There are various methods p roposed to produce FGM components. In particular, solid freeform fabrication ( SFF) methods are commonly used to directly fabricate an FGM part in an additive fashion directly from a computer controlled, layer-by-layer, additive process in which a standard CAD is sliced into a series of horizontal planes. Common SF F techniques being investigated include three-dimensional printing (3DP), Lamin ate Object Manufacturing (LOM), Extrusion Freeform Fabrication (EFF), Selective Laser Sintering (SLS) and even Stereolithography (SL). Fig.1 Current CAE design workflow Fig.2 Proposed CAE design workflow for FGM Albeit the feasibility to fabricate FGM components, one gap still needs to be fi lled for real life FGM product design; namely, where and how to grade the compon ent. This paper will, thus, address issues on incorporating FGM for design impr ovement. Rather than changing the geometry or reselecting a new material, a FGM approach can be employed in design enhancement as shown in Fig.2. The same geo metry and material is retained except that functional property in needed regions is selectively reinforced. As in conventional workflow, CAE simulation is perf ormed after CAD modelling. CAE simulation is preferred since physical test is v ery expensive and most of them are destructive. Moreover, the experience of the engineers may not be accurate. More importantly, the result of CAE simulation is used in this research to produce a stress intensity map for selective reinfor cement. The map will be converted to tool path control signals for generating FG component via SFF machine. On the implementation side, SolidWorks is used fo r CAD modeling, COSMOS/Works is used for CAE simulation. The model is then selec tively reinforced according to the simulation result to produce a FGM enriched p ath plan to drive the Z-corp machine. Case studies are performed to verify the approach. The preliminary result is positive. Future extension to material oth er than starch and plaster powders and enhancement other than stress distributio n may be explored. In conclusion, a CAE-based methodology for FGM product des ign
文摘Rutile phase exhibits higher refractive index and h id ing power, good chemical stability, and is becoming a candidate material for the high-temperature separation and catalysis applications. The thermodynamically stable feature of rutile among the three polymorphs of TiO 2 usually hinders ob taining nano-sized rutile phase by a conventional calcining way. However, acid peptization of amorphous TiO 2 is favorable to the formation of rutile phase. I n this work, well-crystallized and well-dispersed rod-like rutile particles w ith specific surface areas of 49.1 and 35.0 m 2/g were prepared by hydrothermal ly treating the acid peptized TiO 2 amorphous sols at relatively low temperatur es of 200 ℃ or 240 ℃, respectively. The formation of non-touching rutile part icles is attributed to high long-range electrostatic forces between particles i n the presence of the high concentration of the peptizer. The acid peptization w ould easily break the ≡Ti-O-Ti≡ bonds to form ≡Ti-OH or HO-Ti-OH species depending on the amount of acid, and create conditions for the formation of rut ile nuclei after structural rearrangements.
文摘Cordierite is a promising low-k material in mi cr oelectronic and packaging industries. When it is co-fired with the metal for re alising the multilayer circuits, temperature should be low enough to prevent the melting and/or oxidising of the metal. However, this temperature is usually too low to sinter cordierite. Low melting point glass, therefore, is added to the s toichiometric cordierite to lower the sintering temperature through a liquid-si ntering process. In this research work, cordierite-based glass ceramics tapes were prepared by t ape casting from suspensions containing different solids loading and different m ean particle sizes. The optimal experimental conditions for obtaining homogenous green tapes were determined by varying the type and concentration of dispersant s and binders, the solids loading as well as the particle sizes of both cordieri te and glass. Scanning electron microscopy (SEM) and Hg porosimetry were used to characterise the green tapes. The results showed that high values of solids vol ume fractions and of the size ratio between the mean particle sizes of glass and cordierite powders favour the obtaining of homogeneous and high dense substrate s. The dielectric constant of the sintered bodies at 1 100 ℃ was around 5 and t he dissipation factor was about 0.01 at 1 MHz.
文摘Hyperledger Fabric是一个主流的联盟链平台,当面临多笔并发执行且相互关联的交易时,现有架构容易生成大量无效交易,这严重降低了系统的有效交易处理能力。为了解决这一问题,提出一种融合映射与有向无环图(DAG)的冲突消除机制—FabricIMD(Fabric integrated with map and DAG)。该机制在背书节点处通过映射识别交易间依赖关系,并使用有向无环图对此关系进行构建,以调整交易背书顺序,从而有效避免了交易冲突现象的出现。实验证明,当存在多笔相互关联的并发交易时,FabricIMD机制能显著减少因交易冲突导致的无效交易。随着交易间冲突程度的变化,系统有效交易吞吐量提升了15.68%~96.08%。此外,在处理无关联的并发交易时,引入该机制并未对系统性能造成显著影响。综上,FabricIMD机制在避免交易冲突现象出现的同时提高了系统有效交易吞吐量,减少了无效交易数量。
文摘Despite numerous research investigations to understand the influences of various structural parameters,to the authors'knowledge,no research has been the effect of different angles of incidence on stab response and performance of different types of protective textiles.Three distinct structures of 3D woven textiles and 2D plain weave fabric made with similar high-performance fiber and areal density were designed and manufactured to be tested.Two samples,one composed of a single and the other of 4-panel layers,from each fabric type structure,were prepared,and tested against stabbing at[0○],[22.5○],and[45○]angle of incidence.A new stabbing experimental setup that entertained testing of the specimens at various angles of incidence was engineered and utilized.The stabbing bench is also equipped with magnetic sensors and a UK Home Office Scientific Development Branch(HOSDB)/P1/B sharpness engineered knives to measure the impact velocity and exerted impact energy respectively.A silicon compound was utilized to imprint the Back Face Signature(BFS)on the backing material after every specimen test.Each silicon print was then scanned,digitized,and precisely measured to evaluate the stab response and performance of the specimen based on different performance variables,including Depth of Trauma(DOT),Depth of Penetration(DOP),and Length of Penetration(LOP).Besides,the post-impact surface failure modes of the fabrics were also measured using Image software and analyzed at the microscale level.The results show stab angle of incidence greatly influences the stab response and performance of protective textiles.The outcome of the study could provide not only valuable insights into understanding the stab response and capabilities of protective textiles under different angle of incidence,but also provide valuable information for protective textile manufacturer,armor developer and stab testing and standardizing organizations to consider the angle of incidence while developing,testing,optimizing,and using protective textiles in various applications.
基金National Natural Science Foundation of China(Grant Nos.12172179,11802141 and U2341244)National Natural Science Foundation for Young Scientists of China(Grant No.12202207)+3 种基金China Postdoctoral Science Foundation(Grant No.2022M711623)Natural Science Foundation of Jiangsu Province(Grant No.BK20220968)Open Funds for Key Laboratory of Impact and Safety Engineering(Ningbo University),Ministry of Education(Grant No.CJ202201)Open Funds for Shock and Vibration of Engineering Materials and Structures Key Laboratory of Sichuan Province(Grant No.22kfgk03)。
文摘Aramid fibers,due to their relatively high inter-yarn friction,high strength,high modulus,and other characteristics,have become a typical representative of flexible anti-ballistic materials in modern warfare.Current research on the anti-penetration of aramid fabrics mostly focuses unilaterally on the structure and performance of aramid fabrics or the shape and size of projectiles,with fewer studies on the coupled effect of both on ballistic performance.This study analyzes how the coupling relationship(or size effect)between the projectile and fiber bundle dimensions affects the fabric ballistic performance from a mesoscopic scale perspective.Taking plain weave aramid fabric as the research object,considering different diameter projectiles,through a large number of ballistic impact tests and numerical simulations,parameters such as ballistic limit velocity,average energy absorption of fabric,and specific energy absorption ratio(average energy absorption of fabric divided by projectile cross-sectional area)are obtained for ballistic performance analysis.The influence law of projectile size on the ballistic performance of high-performance fabrics is as follows:The relative range of fitted ballistic limit velocity at different target positions gradually decreases and then stabilizes as the projectile diameter increases,indicating that the fabric structure effect gradually disappears at a projectile diameter of 12 mm;The average ballistic limit velocity at three impact positions,P1,P2,and P3,provides the corresponding ballistic limit velocity for 1000D aramid fabric,which increases with projectile diameter but the rate of increase slows down at an inflection point,which in this study occurs where the fabric structure effect nearly disappears at a projectile diameter of 12 mm;The energy absorption ratio increases and then decreases as the projectile diameter increases from 4 mm to 20 mm,reaching a peak at the diameter of 12 mm due to the gradual disappearance of the fabric structural effect.The projectile diameter of 12 mm corresponds to the coupling size of 11.159,which provides a size design reference for the macroscopic-based continuum models of aramid plain weave fabrics.
基金the Major Science and Technology Demonstration Projects in Jiangsu Province(Grant No.BE2022608).
文摘Inspired by the thermal stability mechanism of thermophilic protein,which presents ionic bonds that have better stability at higher temperatures,this paper proposes the introduction of electrostatic interactions by adding carboxyl-modified silica(C-SiO2),PAA,and CaCl_(2) to achieve higher viscosity over 25℃.The rheological behavior of C-SiO_(2)-based shear thickening fluid(CS-STF)was investigated at a temperature range of 25–55℃.Unlike SiO_(2)-based STF,which exhibits single-step thickening and a negative correlation between viscosity and temperature.As the C-SiO_(2) content was 41%(w/w)and the mass ratio of PAA:CaCl_(2):C-SiO_(2) was 3:1:10,the CS-STF displayed a double-thickening behavior,and the peak viscosity reached 1330 Pa·s at 35℃.From the yarn pull-out test,the inter-yarn force was significantly increased with the increasing CS-STF content.Treating UHMWPE fabrics with CS-STF improved the impact resistance effectively.In the blunt impact test,the U-CS fabrics with high CS-STF content(121.45 wt%)experienced penetration failure under high impact energy(18 J)due to stress concentration caused by the shear thickening behavior.The knife stabbing test demonstrated that U-CS fabrics with appropriate content(88.38 wt%)have the best stabbing resistance in various impact energies.Overall,this study proposed a high-performence STF showing double-thickening and enhancing shear-thickening behavior at a wide temperature range,the composite fabrics with the performance of resisting both the blunt and stab impact had broad application prospects in the field of personal protection.
基金Defence Research and Development Establishment(DRDE),DRDO,Gwalior-474002,(India)for his keen interestencouragement.The DRDE accession number for this manuscript is DRDE-IREC-130-28/03/2024.
文摘Chemical warfare agents(CWAs)are extremely lethal substances used in warfare and terrorism,capable of causing permanent damage even in small doses,despite medical intervention.Therefore,detection,protection,and detoxification of CWAs are vital for the safety of first responders,military personnel,and civilians,driving significant research in this area.Herein,we designed and synthesized a poly(-diallyldimethylammonium chloride)(PDDA)mediated cupric oxide(CuO)functionalized activated carbon fabric(ACF),termed ACF@PDDA-CuO,as an adsorbent filter material for self-detoxifying chemical protective clothing.PDDA,a positively charged polyelectrolyte,effectively binds in-situ synthesized CuO to the negatively charged ACF surface,serving as a suitable binder.This study demonstrates the synergistic effects of PDDA-CuO functionalization on ACF,where PDDA treatment enhanced mechanical and comfort properties,and CuO crystal growth significantly improved detoxification efficacy against the CWA Nerve Agent Sarin.Comprehensive analyses,including FTIR,BET surface area analysis,SEM,EDS,TEM,STEM,TGA,XPS,and XRD,confirmed the uniform deposition of CuO and PDDA on the ACF surface.The Cu content on ACF@PDDA-CuO samples was measured via iodometric titration.The materials were evaluated for tensile strength,air permeability,water vapor permeability,nerve agent(Sarin)detoxification,and blister agent(Sulfur Mustard)breakthrough time to assess their applicability for protective clothing.The optimized PDDA-CuO on ACF detoxified 82.04%of Sarin within 18 h,compared to 25.22%by ACF alone,and enhanced tensile strength by 23.67%,air permeability by 24.63%,and water vapor permeability by 3.94%,while maintaining protection against Sulfur Mustard for 24 h.These findings indicate that ACF@PDDA-CuO is a promising candidate for CWA protective clothing,offering robust protection with enhanced comfort.
文摘Stab-resistant textiles play a critical role in personal protection,necessitating a deeper understanding of how structural and layering factors influence their performance.The current study experimentally examines the effects of textile structure,layering,and ply orientation on the stab resistance of multi-layer textiles.Three 3D warp interlock(3DWI)structures({f1},{f2},{f3})and a 2D woven fabric({f4}),all made of high-performance p-aramid yarns,were engineered and manufactured.Multi-layer specimens were prepared and subjected to drop-weight stabbing tests following HOSBD standards.Stabbing performance metrics,including Depth of Trauma(DoT),Depth of Penetration(DoP),and trauma deformation(Ymax,Xmax),were investigated and analyzed.Statistical analyses(Two-and One-Way ANOVA)indicated that fabric type and layer number significantly impacted DoP(P<0.05),while ply orientation significantly affected DoP(P<0.05)but not DoT(P>0.05).Further detailed analysis revealed that 2D woven fabrics exhibited greater trauma deformation than 3D WIF structures.Increasing the number of layers reduced both DoP and DoT across all fabric structures,with f3 demonstrating the best performance in multi-layer configurations.Aligned ply orientations also enhanced stab resistance,underscoring the importance of alignment in dissipating impact energy.
文摘随着区块链技术应用的普及,联盟链Hyperledger Fabric(简称Fabric)已成为知名区块链开源平台,并得到广泛关注.然而Fabric仍受困于并发事务间冲突问题,冲突发生时会引发大量无效交易上链,导致吞吐量下降,阻碍其发展.对于该问题,现有面向块内冲突的方案缺乏高效的冲突检测和避免方法,同时现有研究往往忽略区块间冲突对吞吐量的不利影响.提出了一种Fabric的优化方案Fabric-HT(fabric with high throughput),从区块内和区块间2方面入手,有效降低事务间并发冲突和提高系统吞吐量.针对区块内事务冲突,提出了一种事务调度机制,根据块内冲突事务集定义了一种高效数据结构——依赖关系链,识别具有“危险结构”的事务并提前中止,合理调度事务和消除冲突;针对区块间事务冲突,将冲突事务检测提前至排序节点完成,建立以“推送-匹配”为核心的冲突事务早期避免机制.在多场景下开展大量实验,结果表明Fabric-HT在吞吐量、事务中止率、事务平均执行时间、无效事务空间占用率等方面均优于对比方案.Fabric-HT吞吐量最高可达Fabric的9.51倍,是最新优化方案FabricSharp的1.18倍;空间利用率上相比FabricSharp提升了14%.此外,Fabric-HT也表现出较好的鲁棒性和抗攻击能力.
