Food additive is a double-edged sword. It has merits and demerits. Food additives have such merits as improving sensory properties of foods,preventing deterioration and extending the shelf life,increasing varieties of...Food additive is a double-edged sword. It has merits and demerits. Food additives have such merits as improving sensory properties of foods,preventing deterioration and extending the shelf life,increasing varieties of foods,enhancing convenience of foods,facilitating food processing,and satisfying other demands. However,excessive and illegal use of food additives will exert adverse influence on food security.Therefore,it is required to take proper measures to bring merits of food additives into full play,and get rid of their demerits.展开更多
In a recent issue of the Journal of Sport and Health Science,García-Pinillos et al.~1 reviewed evidence on the effects of highintensity intermittent training(interval training)(HIIT)on muscular and performance ad...In a recent issue of the Journal of Sport and Health Science,García-Pinillos et al.~1 reviewed evidence on the effects of highintensity intermittent training(interval training)(HIIT)on muscular and performance adaptations in recreational runners.展开更多
With growing tendency and widespread application, TBLT has attracted considerable attention from educator teachers,theorists and researchers. The paper commences by offering some influential definitions of‘task',...With growing tendency and widespread application, TBLT has attracted considerable attention from educator teachers,theorists and researchers. The paper commences by offering some influential definitions of‘task', varying classifications of differ-ent types of task, and criteria for judging a task. Then, compared with teaching approaches before the emergence of CLT, TBLT isnew and has many distinct merits. Meanwhile, since it is a newly-established approach, some problems and difficulties in comple-menting TBLT are inevitable. A number of genuine issues raised in Asian language teaching classrooms are examined.展开更多
Aristotle's Poetics represents the first major work of literature criticism. In this masterpiece,Aristotle expresses his literary and aesthetical theories. By introducing the merits in Aristotle's Poetics,this...Aristotle's Poetics represents the first major work of literature criticism. In this masterpiece,Aristotle expresses his literary and aesthetical theories. By introducing the merits in Aristotle's Poetics,this thesis tends to reveal Aristotle's large and enduring influence on modern literary criticism.展开更多
Task-based language teaching is very popular in the modern English teaching.It is based on the Task-based Syllabus. Task-based Syllabus focuses on the learners' communicative competence,which stresses learning by ...Task-based language teaching is very popular in the modern English teaching.It is based on the Task-based Syllabus. Task-based Syllabus focuses on the learners' communicative competence,which stresses learning by doing. From the theoretical assumption and definitions of the task,the paper analysizes the components of the task, then points out the merits and demerits of the syllabus. By this means the paper may give some tips to teachers and students when they use the tsk-based language teaching.展开更多
Two-dimensional nanostructures shed new light on the enhancement of the thermoelectric figure of merit due to the potential decoupling of electronic and phononic transport coefficients.In contrast to the gapless chara...Two-dimensional nanostructures shed new light on the enhancement of the thermoelectric figure of merit due to the potential decoupling of electronic and phononic transport coefficients.In contrast to the gapless character of graphene-like silicene,a recently reported silicon allotropy with a honeycomb-kagome lattice is a semiconductor.Here,based on first-principles calculations,we set out to investigate the thermoelectric transport performance of this semiconducting silicene.Since the mean free path of a large number of phonons in this structure is less than the Ioffe–Regel limit,we employ the quantum Boltzmann transport equation(BTE)method to obtain an accurate prediction of lattice thermal conductivity.Importantly,we unexpectedly find much lower lattice thermal conductivity compared to that of graphene-like silicene,i.e.,about 1.73W·m^(−1)·K^(−1)at room temperature.Meanwhile,the electronic transport coefficient is calculated within the strictly electron–phonon coupling calculation and a full solution of the electron BTE.The optimal thermoelectric figure of merit ZT reaches 3.2 in N-doped silicene at 700K with an optimized low carrier concentration of 8×10^(10)cm^(−2),which is a recorded value among two-dimensional materials.Our work paved the way for applications of silicon-based two-dimensional materials in on-chip thermoelectric cooling and clean energy.展开更多
Spintronic technology and energy applications benefit greatly from the exceptional characteristics of rare-earth-based spinel chalcogenides.Examining the electrical,magnetic and thermoelectric properties of HgNd_(2)Z_...Spintronic technology and energy applications benefit greatly from the exceptional characteristics of rare-earth-based spinel chalcogenides.Examining the electrical,magnetic and thermoelectric properties of HgNd_(2)Z_(4)(Z=S,Se)in a systematic manner is essential for the strategic advancement of spin polarized current in a spintronic device.In this recent study,the WIEN2K code was employed to comprehensively analyze these properties.The calculated lattice constants,obtained using the generalized gradient approximation(GGAsol-PBE),closely match experimental findings of the similar family compounds.The examination of the stability of ferromagnetic states in the ground state involves comparing energies between anti-ferromagnetic and ferromagnetic states.Moreover,an assessment of the stability of the cubic phase in both spinels was conducted using analyses of the phonon dispersion curve,formation energy and Born stability criteria.The ductility characteristics were examined through the calculation of Poisson's and Pugh's ratios.Furthermore,details regarding the density of states,spin polarization,ex-change coupling and Curie temperature were provided to explore the characteristics associated with ferromagnetism.Potential optoelectronic applications were proposed,leveraging the direct band gaps of 1.4 and 1.0 eV for HgNd_(2)Z_(4)(Z=S,Se)respectively,within the visible spectrum.Particularly noteworthy is the effective light absorption of HgNd2Se4 in the visible range,characterized by prominent peaks that facilitate the transition of electrons from the valence band(VB)to the conduction band(CB).Additionally,the study extends to thermoelectric characteristics,determining various factors such as Seebeck coef-ficient(S),figure of merit(ZT),electrical and thermal conductivities of the evaluated spinels.展开更多
The layered PbBi_(4)Te_(7) compound is considered a promising thermoelectric material due to its unusually high electrical transport properties in ternary compound systems.However,its high carrier concentration leads ...The layered PbBi_(4)Te_(7) compound is considered a promising thermoelectric material due to its unusually high electrical transport properties in ternary compound systems.However,its high carrier concentration leads to relatively high thermal conductivity and low Seebeck coefficient,limiting the enhancement of its thermoelectric performance.In this work,we introduce Se alloying and Cu doping to synergistically regulate the thermoelectric transport properties of PbBi_(4)Te_(7).Se alloying induces strong lattice contraction and increased interlayer electron scattering,significantly reducing lattice thermal conductivity while enhancing the Seebeck coefficient.Besides,Cu doping forms interlayer electron transport channels thus optimizing carrier mobility and electrical transport properties.Cu substitution also enhances point defect scattering further suppressing phonon transport.Ultimately,the strong anharmonic structure formed by Se alloying and Cu-induced phonon scattering results in a remarkably low lattice thermal conductivity of 0.27 W m^(−1) K^(−1) at 300 K in PbBi_(4)Te_(5)Se_(2)-0.1%Cu samples.The maximum thermoelectric figure of merit(ZT_(max))is increased to 0.68,with an average thermoelectric figure of merit(ZTave)of 0.56 in the near-room temperature range(300–573 K),outperforming other typical ternary Pb-Bi-based compounds.展开更多
Task-based language teaching approach(TBLTA), which lays stress on "learning by doing", gained increasing popularity in English teaching in recent years. The design of phonetic teaching calls for more emphas...Task-based language teaching approach(TBLTA), which lays stress on "learning by doing", gained increasing popularity in English teaching in recent years. The design of phonetic teaching calls for more emphasis from English educators since it is one of the basic rounds of English teaching. This paper made a trial on the utilization of TBLTA in the English phonetic teaching context and designed a TBLTA model for English phonetic teaching based on discussions about model and merits of TBLTA.展开更多
Role of Bariatric surgery for obesity is briefly outlined. Selection criteria, contraindications, evaluations of patients before surgery, types of bariatric surgery with their merits and demerits are discussed. Result...Role of Bariatric surgery for obesity is briefly outlined. Selection criteria, contraindications, evaluations of patients before surgery, types of bariatric surgery with their merits and demerits are discussed. Results of lifestyle modifications is compared with that of bariatric surgery.展开更多
As the amount of data continues to grow rapidly,the variety of data produced by applications is becoming more affluent than ever.Cloud computing is the best technology evolving today to provide multi-services for the ...As the amount of data continues to grow rapidly,the variety of data produced by applications is becoming more affluent than ever.Cloud computing is the best technology evolving today to provide multi-services for the mass and variety of data.The cloud computing features are capable of processing,managing,and storing all sorts of data.Although data is stored in many high-end nodes,either in the same data centers or across many data centers in cloud,performance issues are still inevitable.The cloud replication strategy is one of best solutions to address risk of performance degradation in the cloud environment.The real challenge here is developing the right data replication strategy with minimal data movement that guarantees efficient network usage,low fault tolerance,and minimal replication frequency.The key problem discussed in this research is inefficient network usage discovered during selecting a suitable data center to store replica copies induced by inadequate data center selection criteria.Hence,to mitigate the issue,we proposed Replication Strategy with a comprehensive Data Center Selection Method(RS-DCSM),which can determine the appropriate data center to place replicas by considering three key factors:Popularity,space availability,and centrality.The proposed RS-DCSM was simulated using CloudSim and the results proved that data movement between data centers is significantly reduced by 14%reduction in overall replication frequency and 20%decrement in network usage,which outperformed the current replication strategy,known as Dynamic Popularity aware Replication Strategy(DPRS)algorithm.展开更多
Intermittent exotropia with convergence insufficiency is defined as a greater exodeviation measured at near than at distance of at least 10 prism diopters and it is harmful to binocular vision at earlier time. This pa...Intermittent exotropia with convergence insufficiency is defined as a greater exodeviation measured at near than at distance of at least 10 prism diopters and it is harmful to binocular vision at earlier time. This paper mainly introduces three operation patterns including lateral rectus recession(s) with or without a slanting procedure, unilateral lateral rectus recession with medial rectus resection, and medial rectus resection(s) with or without a slanting procedure.展开更多
Multimodal as digital literacies are,they have still been text-based.It has been a great concern that due to the popularity of speech-like writing style online,digital literacies have brought informal speech expressio...Multimodal as digital literacies are,they have still been text-based.It has been a great concern that due to the popularity of speech-like writing style online,digital literacies have brought informal speech expressions into formal standard writing,and thus increasing the possibility to ruin the standard writing language.On the other hand,although there are moral panics of the survival of standard written languages,scholars and popular media show great tolerance for online languages.In addition,it has been proved that some frequent participants in digital literacies nowadays are capable of both online language and standard offline language,indicating that they are well aware of the different registers of language use and therefore of high language literacy.Furthermore,researches suggest several possible merits of digital literacies,including saving young people from social isolation and depression,providing people with more opportunities to learn new things and to practice the instructional writing,calling for thorough consideration and elaborate editing and encouraging brief and clear writing style.展开更多
A new ultralow gate–drain charge(Q_(GD)) 4 H-SiC trench MOSFET is presented and its mechanism is investigated by simulation. The novel MOSFET features double shielding structures(DS-MOS): one is the grounded split ga...A new ultralow gate–drain charge(Q_(GD)) 4 H-SiC trench MOSFET is presented and its mechanism is investigated by simulation. The novel MOSFET features double shielding structures(DS-MOS): one is the grounded split gate(SG), the other is the P+shielding region(PSR). Both the SG and the PSR reduce the coupling effect between the gate and the drain, and transform the most part of the gate–drain capacitance(C_(GD)) into the gate–source capacitance(C_(GS)) and drain–source capacitance(C_(DS)) in series.Thus the C_(GD) is reduced and the proposed DS-MOS obtains ultralow Q_(GD). Compared with the double-trench MOSFET(DT-MOS)and the conventional trench MOSFET(CT-MOS), the proposed DS-MOS decreases the Q_(GD) by 85% and 81%, respectively.Moreover, the figure of merit(FOM), defined as the product of specific on-resistance(R_(on, sp)) and Q_(GD)(R_(on, sp)Q_(GD)), is reduced by 84% and 81%, respectively.展开更多
This paper investigates the effects of pH on stability and thermal properties of copper oxide(CuO),graphene oxide(GO),and their hybrid nanofluid(HNF)at different mixing ratios.Initially,sol-gel and Hummer’s method wa...This paper investigates the effects of pH on stability and thermal properties of copper oxide(CuO),graphene oxide(GO),and their hybrid nanofluid(HNF)at different mixing ratios.Initially,sol-gel and Hummer’s method was employed for the synthesis of CuO and GO nanoparticles(NPs),and they are characterized with various techniques.The effects of two different surfactants were analyzed on nanofluid’s(NF’s)stability at different pH values.The properties like thermal conductivity(TC)and viscosity(VST)of NFs were measured at different volume concentration(0.1 vol%to 1.0 vol%)and temperature range of 30-60℃,respectively.The TC and VST of GO/CuO(50:50)HNF are higher than that of GO/CuO(20:80).The figure of merit(FOM)is determined for the studied HNFs.The correlations were presented to calculate the TC as well as VST of HNFs.Two modern novel machine learning-based ensemble approaches were employed for predictive model development for TC and VST of considered HNFs.The comparison of prognostic models with Taylor’s diagram revealed that Bayesian optimized support vector machine(BoASVM)was superior to Bayesian optimized boosted regression trees(BoA-BRT)for both TC and VST models.展开更多
We obtained TiNiSn-based half-Heusler Hf_(x)Ti_(1-x)NiSn_(0.97)Sb_(0.03)bulks with 85%-96%relative densities via 5-min microwave synthesis and 20-min microwave sintering in sealed vacuum.The phase composition and micr...We obtained TiNiSn-based half-Heusler Hf_(x)Ti_(1-x)NiSn_(0.97)Sb_(0.03)bulks with 85%-96%relative densities via 5-min microwave synthesis and 20-min microwave sintering in sealed vacuum.The phase composition and microstructure of samples were characterized by X-ray diffractometer(XRD)and scanning electron microscopy(SEM).Thermoelectric(TE)properties were measured,i.e.,Seebeck coefficient(S),electrical resistivity(ρ),and thermal conductivity(κ)through Seebeck coefficient/resistance analysis system(S/RAs)and laser flash thermal analyzer(LFT).The results show that the nearly single phase exists after microwave sintering.The grain sizes and the number of grain boundaries decrease with increase in Hf-doping amount due to an increase in point defects.The matrix grains for Hf_(0.1)Ti_(0.9)NiSn_(0.97)Sb_(0.03)are~10μm.The nanoscle pores and precipitates are present as second phases in matrix grain.The real composition for Hf_(0.1)Ti_(0.9)NiSn_(0.97)Sb_(0.03)matrix grain is Hf_(3.51)Ti_(28.76)-Ni_(34.76)Sn_(31.55)Sb_(1.43).The variation trends of electrical resistivity,Seebeck coefficient,power factor,and thermal conductivity were analyzed in detail.The maximum figure of merit(ZT)of 0.46 is obtained for Hf_(0.1)Ti_(0.9-)NiSnSn_(0.97)Sb_(0.03)at 723 K.The innovation route exhibits advantages for predation of TE bulks when compared to the conventional methods,especially in terms of efficiency while it still maintains TE performance.展开更多
文摘Food additive is a double-edged sword. It has merits and demerits. Food additives have such merits as improving sensory properties of foods,preventing deterioration and extending the shelf life,increasing varieties of foods,enhancing convenience of foods,facilitating food processing,and satisfying other demands. However,excessive and illegal use of food additives will exert adverse influence on food security.Therefore,it is required to take proper measures to bring merits of food additives into full play,and get rid of their demerits.
文摘In a recent issue of the Journal of Sport and Health Science,García-Pinillos et al.~1 reviewed evidence on the effects of highintensity intermittent training(interval training)(HIIT)on muscular and performance adaptations in recreational runners.
文摘With growing tendency and widespread application, TBLT has attracted considerable attention from educator teachers,theorists and researchers. The paper commences by offering some influential definitions of‘task', varying classifications of differ-ent types of task, and criteria for judging a task. Then, compared with teaching approaches before the emergence of CLT, TBLT isnew and has many distinct merits. Meanwhile, since it is a newly-established approach, some problems and difficulties in comple-menting TBLT are inevitable. A number of genuine issues raised in Asian language teaching classrooms are examined.
文摘Aristotle's Poetics represents the first major work of literature criticism. In this masterpiece,Aristotle expresses his literary and aesthetical theories. By introducing the merits in Aristotle's Poetics,this thesis tends to reveal Aristotle's large and enduring influence on modern literary criticism.
文摘Task-based language teaching is very popular in the modern English teaching.It is based on the Task-based Syllabus. Task-based Syllabus focuses on the learners' communicative competence,which stresses learning by doing. From the theoretical assumption and definitions of the task,the paper analysizes the components of the task, then points out the merits and demerits of the syllabus. By this means the paper may give some tips to teachers and students when they use the tsk-based language teaching.
基金supported by the Scientific and Technological Research of the Chongqing Municipal Education Commission(Grant No.KJZD-K202100602)the funding from the Institute for Advanced Sciences of Chongqing University of Posts and Telecommunications(Grant No.E011A2022326)partially supported by the RIE2020 Advanced Manufacturing and Engineering(AME)Programmatic(Grant No.A1898b0043 for G.Z.)。
文摘Two-dimensional nanostructures shed new light on the enhancement of the thermoelectric figure of merit due to the potential decoupling of electronic and phononic transport coefficients.In contrast to the gapless character of graphene-like silicene,a recently reported silicon allotropy with a honeycomb-kagome lattice is a semiconductor.Here,based on first-principles calculations,we set out to investigate the thermoelectric transport performance of this semiconducting silicene.Since the mean free path of a large number of phonons in this structure is less than the Ioffe–Regel limit,we employ the quantum Boltzmann transport equation(BTE)method to obtain an accurate prediction of lattice thermal conductivity.Importantly,we unexpectedly find much lower lattice thermal conductivity compared to that of graphene-like silicene,i.e.,about 1.73W·m^(−1)·K^(−1)at room temperature.Meanwhile,the electronic transport coefficient is calculated within the strictly electron–phonon coupling calculation and a full solution of the electron BTE.The optimal thermoelectric figure of merit ZT reaches 3.2 in N-doped silicene at 700K with an optimized low carrier concentration of 8×10^(10)cm^(−2),which is a recorded value among two-dimensional materials.Our work paved the way for applications of silicon-based two-dimensional materials in on-chip thermoelectric cooling and clean energy.
基金the Deanship of Scientific Research at King Khalid University for funding this work through large group Research Project under grant number RGP2/450/44。
文摘Spintronic technology and energy applications benefit greatly from the exceptional characteristics of rare-earth-based spinel chalcogenides.Examining the electrical,magnetic and thermoelectric properties of HgNd_(2)Z_(4)(Z=S,Se)in a systematic manner is essential for the strategic advancement of spin polarized current in a spintronic device.In this recent study,the WIEN2K code was employed to comprehensively analyze these properties.The calculated lattice constants,obtained using the generalized gradient approximation(GGAsol-PBE),closely match experimental findings of the similar family compounds.The examination of the stability of ferromagnetic states in the ground state involves comparing energies between anti-ferromagnetic and ferromagnetic states.Moreover,an assessment of the stability of the cubic phase in both spinels was conducted using analyses of the phonon dispersion curve,formation energy and Born stability criteria.The ductility characteristics were examined through the calculation of Poisson's and Pugh's ratios.Furthermore,details regarding the density of states,spin polarization,ex-change coupling and Curie temperature were provided to explore the characteristics associated with ferromagnetism.Potential optoelectronic applications were proposed,leveraging the direct band gaps of 1.4 and 1.0 eV for HgNd_(2)Z_(4)(Z=S,Se)respectively,within the visible spectrum.Particularly noteworthy is the effective light absorption of HgNd2Se4 in the visible range,characterized by prominent peaks that facilitate the transition of electrons from the valence band(VB)to the conduction band(CB).Additionally,the study extends to thermoelectric characteristics,determining various factors such as Seebeck coef-ficient(S),figure of merit(ZT),electrical and thermal conductivities of the evaluated spinels.
基金financial support from the National Natural Science Foundation of China(Grant No.52172236 and No.22205032)the Fund of the State Key Laboratory of Solidification Processing in NPU(Grant No.SKLSP202314)supported by“Bairen”Program from University of Electronic Science and Technology of China.
文摘The layered PbBi_(4)Te_(7) compound is considered a promising thermoelectric material due to its unusually high electrical transport properties in ternary compound systems.However,its high carrier concentration leads to relatively high thermal conductivity and low Seebeck coefficient,limiting the enhancement of its thermoelectric performance.In this work,we introduce Se alloying and Cu doping to synergistically regulate the thermoelectric transport properties of PbBi_(4)Te_(7).Se alloying induces strong lattice contraction and increased interlayer electron scattering,significantly reducing lattice thermal conductivity while enhancing the Seebeck coefficient.Besides,Cu doping forms interlayer electron transport channels thus optimizing carrier mobility and electrical transport properties.Cu substitution also enhances point defect scattering further suppressing phonon transport.Ultimately,the strong anharmonic structure formed by Se alloying and Cu-induced phonon scattering results in a remarkably low lattice thermal conductivity of 0.27 W m^(−1) K^(−1) at 300 K in PbBi_(4)Te_(5)Se_(2)-0.1%Cu samples.The maximum thermoelectric figure of merit(ZT_(max))is increased to 0.68,with an average thermoelectric figure of merit(ZTave)of 0.56 in the near-room temperature range(300–573 K),outperforming other typical ternary Pb-Bi-based compounds.
文摘Task-based language teaching approach(TBLTA), which lays stress on "learning by doing", gained increasing popularity in English teaching in recent years. The design of phonetic teaching calls for more emphasis from English educators since it is one of the basic rounds of English teaching. This paper made a trial on the utilization of TBLTA in the English phonetic teaching context and designed a TBLTA model for English phonetic teaching based on discussions about model and merits of TBLTA.
文摘Role of Bariatric surgery for obesity is briefly outlined. Selection criteria, contraindications, evaluations of patients before surgery, types of bariatric surgery with their merits and demerits are discussed. Results of lifestyle modifications is compared with that of bariatric surgery.
基金supported by Universiti Putra Malaysia and the Ministry of Education(MOE).
文摘As the amount of data continues to grow rapidly,the variety of data produced by applications is becoming more affluent than ever.Cloud computing is the best technology evolving today to provide multi-services for the mass and variety of data.The cloud computing features are capable of processing,managing,and storing all sorts of data.Although data is stored in many high-end nodes,either in the same data centers or across many data centers in cloud,performance issues are still inevitable.The cloud replication strategy is one of best solutions to address risk of performance degradation in the cloud environment.The real challenge here is developing the right data replication strategy with minimal data movement that guarantees efficient network usage,low fault tolerance,and minimal replication frequency.The key problem discussed in this research is inefficient network usage discovered during selecting a suitable data center to store replica copies induced by inadequate data center selection criteria.Hence,to mitigate the issue,we proposed Replication Strategy with a comprehensive Data Center Selection Method(RS-DCSM),which can determine the appropriate data center to place replicas by considering three key factors:Popularity,space availability,and centrality.The proposed RS-DCSM was simulated using CloudSim and the results proved that data movement between data centers is significantly reduced by 14%reduction in overall replication frequency and 20%decrement in network usage,which outperformed the current replication strategy,known as Dynamic Popularity aware Replication Strategy(DPRS)algorithm.
文摘Intermittent exotropia with convergence insufficiency is defined as a greater exodeviation measured at near than at distance of at least 10 prism diopters and it is harmful to binocular vision at earlier time. This paper mainly introduces three operation patterns including lateral rectus recession(s) with or without a slanting procedure, unilateral lateral rectus recession with medial rectus resection, and medial rectus resection(s) with or without a slanting procedure.
文摘Multimodal as digital literacies are,they have still been text-based.It has been a great concern that due to the popularity of speech-like writing style online,digital literacies have brought informal speech expressions into formal standard writing,and thus increasing the possibility to ruin the standard writing language.On the other hand,although there are moral panics of the survival of standard written languages,scholars and popular media show great tolerance for online languages.In addition,it has been proved that some frequent participants in digital literacies nowadays are capable of both online language and standard offline language,indicating that they are well aware of the different registers of language use and therefore of high language literacy.Furthermore,researches suggest several possible merits of digital literacies,including saving young people from social isolation and depression,providing people with more opportunities to learn new things and to practice the instructional writing,calling for thorough consideration and elaborate editing and encouraging brief and clear writing style.
基金supported by the National Key Research and Development Program of China(No.2016YFB0400502)
文摘A new ultralow gate–drain charge(Q_(GD)) 4 H-SiC trench MOSFET is presented and its mechanism is investigated by simulation. The novel MOSFET features double shielding structures(DS-MOS): one is the grounded split gate(SG), the other is the P+shielding region(PSR). Both the SG and the PSR reduce the coupling effect between the gate and the drain, and transform the most part of the gate–drain capacitance(C_(GD)) into the gate–source capacitance(C_(GS)) and drain–source capacitance(C_(DS)) in series.Thus the C_(GD) is reduced and the proposed DS-MOS obtains ultralow Q_(GD). Compared with the double-trench MOSFET(DT-MOS)and the conventional trench MOSFET(CT-MOS), the proposed DS-MOS decreases the Q_(GD) by 85% and 81%, respectively.Moreover, the figure of merit(FOM), defined as the product of specific on-resistance(R_(on, sp)) and Q_(GD)(R_(on, sp)Q_(GD)), is reduced by 84% and 81%, respectively.
文摘This paper investigates the effects of pH on stability and thermal properties of copper oxide(CuO),graphene oxide(GO),and their hybrid nanofluid(HNF)at different mixing ratios.Initially,sol-gel and Hummer’s method was employed for the synthesis of CuO and GO nanoparticles(NPs),and they are characterized with various techniques.The effects of two different surfactants were analyzed on nanofluid’s(NF’s)stability at different pH values.The properties like thermal conductivity(TC)and viscosity(VST)of NFs were measured at different volume concentration(0.1 vol%to 1.0 vol%)and temperature range of 30-60℃,respectively.The TC and VST of GO/CuO(50:50)HNF are higher than that of GO/CuO(20:80).The figure of merit(FOM)is determined for the studied HNFs.The correlations were presented to calculate the TC as well as VST of HNFs.Two modern novel machine learning-based ensemble approaches were employed for predictive model development for TC and VST of considered HNFs.The comparison of prognostic models with Taylor’s diagram revealed that Bayesian optimized support vector machine(BoASVM)was superior to Bayesian optimized boosted regression trees(BoA-BRT)for both TC and VST models.
基金financially supported by the National Natural Science Foundation of China (Nos.51574134 and 51574042)the Joint Fund between Shenyang National Laboratory for Materials Science and State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals (No.18LHPY016)Anhui University Outstanding Young Talent Support Program (Key Project) (No.gxyq ZD2017039)。
文摘We obtained TiNiSn-based half-Heusler Hf_(x)Ti_(1-x)NiSn_(0.97)Sb_(0.03)bulks with 85%-96%relative densities via 5-min microwave synthesis and 20-min microwave sintering in sealed vacuum.The phase composition and microstructure of samples were characterized by X-ray diffractometer(XRD)and scanning electron microscopy(SEM).Thermoelectric(TE)properties were measured,i.e.,Seebeck coefficient(S),electrical resistivity(ρ),and thermal conductivity(κ)through Seebeck coefficient/resistance analysis system(S/RAs)and laser flash thermal analyzer(LFT).The results show that the nearly single phase exists after microwave sintering.The grain sizes and the number of grain boundaries decrease with increase in Hf-doping amount due to an increase in point defects.The matrix grains for Hf_(0.1)Ti_(0.9)NiSn_(0.97)Sb_(0.03)are~10μm.The nanoscle pores and precipitates are present as second phases in matrix grain.The real composition for Hf_(0.1)Ti_(0.9)NiSn_(0.97)Sb_(0.03)matrix grain is Hf_(3.51)Ti_(28.76)-Ni_(34.76)Sn_(31.55)Sb_(1.43).The variation trends of electrical resistivity,Seebeck coefficient,power factor,and thermal conductivity were analyzed in detail.The maximum figure of merit(ZT)of 0.46 is obtained for Hf_(0.1)Ti_(0.9-)NiSnSn_(0.97)Sb_(0.03)at 723 K.The innovation route exhibits advantages for predation of TE bulks when compared to the conventional methods,especially in terms of efficiency while it still maintains TE performance.
