In this paper, a test system was developed in which a CCD camera was used as a sensor together with an IBM-AT-compatible computer with an Intel 80486 processor to measure the impurities and neps on a piece of cotton g...In this paper, a test system was developed in which a CCD camera was used as a sensor together with an IBM-AT-compatible computer with an Intel 80486 processor to measure the impurities and neps on a piece of cotton gray goods, and a method was proposed by which the differences of degree of gray between samples and interference caused by surface unevenness, creasing and the like within a test sample can be removed effectively. The whole test system is reliable, accurate and causing fewer subjective errors.展开更多
Defect free yarn is a great demand for spinner, knitter, and weaver and also other textile personnel because numerous end products from knit apparels to woven fabrics, from towels to sheets and from carpets to industr...Defect free yarn is a great demand for spinner, knitter, and weaver and also other textile personnel because numerous end products from knit apparels to woven fabrics, from towels to sheets and from carpets to industrial fabrics characteristics significantly depend on the physical properties of yarn. The qualities of rotor yarn are really directed by spinning parameters. The aim of this study is to observe the effect of spinning parameters such as rotor diameter and speed on thick, thin places and neps of yarn in rotor spinning process. 0.11 sliver hank of 100% cotton was used to produce 12 Ne yarn. 65% virgin cotton and 35% wastage cotton were mixed together. The positive impact of spinning parameters on yarn properties were accessed by thick places, thin places and neps. Results indicate that the yarn qualities were improved with increasing of rotor speed and rotor diameter. The rotor diameter was settled to 43 mm while rotor speed fluctuated from 35,000 to 45,000 rpm and rotor speed was fixed to 35,000 rpm while rotor diameter across contrasts from 43 mm to 66 mm.展开更多
甘肃省草地是我国碳收支研究的关键区域,其净生态系统生产力(NEP)是衡量碳源/汇功能的核心。然而复杂的地形和气候条件导致该地区NEP估算存在较大不确定性。本研究基于集成生物圈模型(IBIS),模拟了1980—2022年甘肃省草地NEP的时空格局...甘肃省草地是我国碳收支研究的关键区域,其净生态系统生产力(NEP)是衡量碳源/汇功能的核心。然而复杂的地形和气候条件导致该地区NEP估算存在较大不确定性。本研究基于集成生物圈模型(IBIS),模拟了1980—2022年甘肃省草地NEP的时空格局,并结合观测数据验证了模型精度。结果表明,IBIS模型能够较好地模拟该区域草地NEP动态(R^(2)=0.70,P<0.0001)。1980—2022年,甘肃省草地年均NEP为194.5 g m^(-2)·a^(-1)C,呈轻微上升趋势。年均NEP空间格局总体呈现东南高西北低,从东南向西北逐渐递减的趋势。南部草地大部分地区为碳汇区,北部部分干旱草原为碳源区,其NEP分布格局主要由降雨主导。本研究为甘肃省草地碳汇功能评估提供了科学依据,对实现区域“碳中和”目标具有重要参考价值。展开更多
净生态系统生产力(NEP)是评价区域生态系统碳源碳汇的重要指标,厘清其时空分异格局及驱动机制对京津冀生态系统精准保护与修复至关重要.基于MODIS遥感数据估算了净生态系统生产力(NEP),采用Sen趋势+MK检验、Hurst指数和重心迁移等方法...净生态系统生产力(NEP)是评价区域生态系统碳源碳汇的重要指标,厘清其时空分异格局及驱动机制对京津冀生态系统精准保护与修复至关重要.基于MODIS遥感数据估算了净生态系统生产力(NEP),采用Sen趋势+MK检验、Hurst指数和重心迁移等方法探究了京津冀2002~2020年固碳效益时空格局和演替规律,利用偏相关、复相关及残差分析定量解析了人类活动和气候变化驱动固碳效益时空分异的相对贡献.结果表明:①京津冀近20 a NEP呈逐年上升趋势,增长速率(以C计)为3.066 4g·(m^(2)·a)^(-1),空间上表现为西北高东南低;碳汇能力强的地区主要集中在张家口市和承德市周边,碳源效应强烈的区域分布在天津和邯郸等地;超过80%的区域碳汇能力呈上升趋势,其中极显著上升、显著上升区域占比分别为47.45%和8.29%,尤其是张-承地区,但未来增长趋势在逐步减缓;碳源重心在逐渐向东南部平原迁移,碳汇重心则由东北向西南迁移.②超过50%区域的NEP与年平均气温和年累计降水呈现正相关关系,但显著性均不强,复相关结果进一步证明了存在气象因素之外的其他条件在主导NEP的变化.③研究区域内NEP退化区与改善区占比分别为12.41%、87.59%,残差分析表明人类主导的固碳效益提升区占总改善区的94.88%,而退化区中气候主导的固碳效益降低区占62.84%,说明京津冀地区人类活动在影响生态系统固碳效益方面以正向促进为主.研究结论对精准识别京津冀生态系统保护与修复未来工作重心有指导意义.展开更多
农田生态系统是陆地生态系统的重要组成部分,其碳源汇过程对气候变化的响应非常敏感。然而,当前气候变化及其碳氮耦合作用对农田生态系统碳源汇过程的影响贡献与驱动机制尚不明晰。基于总初级生产力(GPP)、净初级生产力(NPP)和净生态系...农田生态系统是陆地生态系统的重要组成部分,其碳源汇过程对气候变化的响应非常敏感。然而,当前气候变化及其碳氮耦合作用对农田生态系统碳源汇过程的影响贡献与驱动机制尚不明晰。基于总初级生产力(GPP)、净初级生产力(NPP)和净生态系统生产力(NEP)三种碳汇指标,以及系统总呼吸(Rs)、自养呼吸(Ra)和异养呼吸(Rh)三种碳源指标构建6种情景,揭示了中国农田生态系统碳源汇时空演变趋势特征,并基于Lindeman-Merenda-Gold(LMG)模型定量评估了气候变化及其碳氮耦合作用对中国农田生态系统碳源汇变化影响贡献。研究结果表明:(1)2000-2020年中国农田生态系统碳汇与碳源均表现为波动增长趋势,其中GPP、NPP和NEP平均增长率分别为4.27、1.65与0.15 g C m^(-2) a^(-1),Rs、Ra和Rh平均增长率分别为4.12、2.62与1.50 g C m^(-2) a^(-1),由于较高的呼吸作用,中国农田生态系统总体表现为弱碳汇;(2)2000-2020年中国农田生态系统除Rs/GPP以0.12%的速率小幅增长外,NEP/NPP、NEP/GPP及NEP/Rs均呈减少趋势,变化速率分别为-0.28%、-0.39%和-0.46%,呼吸主导作用逐渐加强导致碳汇主导作用减弱;(3)CO_(2)施肥和氮沉降对中国农田生态系统净碳汇增长的贡献为28.98%,主控了25.30%的农田碳汇区域。然而,CO_(2)施肥和氮沉降也导致了中国农田生态系统碳源增强,二者相对贡献率为32.41%,主控了26.75%的农田碳源区域。(4)GPP弱主导机制驱动了中国农田生态系统NEP的增长,GPP是碳汇区(KNEP>0)碳汇增长的主要驱动因子,主控了77.14%的农田碳汇区域。相反,Rs强主导机制导致了中国农田生态系统NEP下降,Rh是碳源区(KNEP<0)碳源增强的主要驱动因子,主控了46.98%的农田碳源区域。研究结果可为巩固提升农田生态系统碳汇,促进碳中和目标实现提供科学依据。展开更多
Teacher education at the foundational and preparatory stages plays a crucial role in shaping early childhood learning experiences.The National Curriculum Framework for School Education(NCFSE)2023 provides a structured...Teacher education at the foundational and preparatory stages plays a crucial role in shaping early childhood learning experiences.The National Curriculum Framework for School Education(NCFSE)2023 provides a structured pedagogical approach to address challenges in these stages.However,despite these policy frameworks,teachers in Kendriya Vidyalayas(KVs)continue to face numerous pedagogical challenges.This paper aims to explore and analyze the pedagogical challenges encountered by KV teachers in foundational and preparatory stage classrooms and compare them with the challenges addressed in NCFSE 2023.Using qualitative research methods,data were collected through structured online interviews with 10 KV teachers from different campuses.This paper investigated various challenges,including classroom management,language barriers,a lack of inclusive education strategies,insufficient infrastructure,limited parental involvement,and difficulties in integrating technology into teaching practices.The findings highlight the gap between policy recommendations and ground-level implementation.Based on these insights,the study suggests recommendations such as specialized teacher training,recruitment of special educators,improved infrastructure,enhanced parental engagement,and policy-driven interventions to bridge the gap between policy frameworks and real-world classroom experiences.The study concludes that addressing these challenges through targeted reforms can create a more inclusive and effective learning environment,fostering holistic student development at the foundational and preparatory stages.展开更多
By combining neuroevolution potential(NEP)with phonon Boltzmann transport theory,we systematically investigate the thermal transport properties of three two-dimensional(2D)narrow bandgap semiconductors:Ca_(3)N_(2),Ba_...By combining neuroevolution potential(NEP)with phonon Boltzmann transport theory,we systematically investigate the thermal transport properties of three two-dimensional(2D)narrow bandgap semiconductors:Ca_(3)N_(2),Ba_(3)P_(2),and Ba_(3)As_(2).The room-temperature lattice thermal conductivities(κ_(L))of Ca_(3)N_(2),Ba_(3)P_(2),and Ba_(3)As_(2)considering only three-phonon scattering are 6.60 W/m K,11.90 W/m K,and 8.88 W/m K,respectively.When taking into account the higherorder phonon(four-phonon)scattering processes,theκL of these three materials decrease to 6.12 W/m K,9.73 W/m K and6.77 W/m K,respectively.Among these systems,Ba_(3)As_(2)undergoes the most pronounced suppression with a reduction of 23.8%.This is mainly due to the greater scattering phase space which enhances the four-phonon scattering.Meanwhile,it is revealed that unlike the traditional evaluation using the P_(4)/P_(3)ratio as an indicator of the strength of four-phonon interactions,the thermal conductivity of Ba_(3)P_(2)exhibits weaker four-phonon suppression behavior compared to Ba_(3)As_(2),despite hosting a higher P_(4)/P_(3)ratio.That is to say,the strength of four-phonon scattering cannot be evaluated solely by the ratio of P_(4)/P_(3).These results presented in this work shed light on the thermal transport properties of such new 2D semiconductors with narrow bandgaps.展开更多
草地碳汇/源是植被生态系统中碳收支和碳平衡的一个重要内容,区分碳汇和碳源对气候变化的响应可为减源增汇提供科学依据。基于MODIS NPP数据和土壤呼吸模型量化了2001—2019年青藏高原草地净生态系统生产力(NEP)的时空变化和碳汇/源格局...草地碳汇/源是植被生态系统中碳收支和碳平衡的一个重要内容,区分碳汇和碳源对气候变化的响应可为减源增汇提供科学依据。基于MODIS NPP数据和土壤呼吸模型量化了2001—2019年青藏高原草地净生态系统生产力(NEP)的时空变化和碳汇/源格局,利用通径分析方法分析了青藏高原气候变化对草地碳汇/源的影响。结果表明:青藏高原草地NEP呈现东高西低的分布格局,年平均值为54.41 g C m^(-2)。草地整体上以碳汇功能为主。碳汇区面积约为72.26万km^(2),碳源区面积约为47.82万km^(2),净碳汇总量65.35 Tg C a^(-1)。近19年青藏高原草地NEP以增加趋势为主,青藏高原气候暖湿化趋势有利于草地NEP的增加,增强碳汇;而暖干化趋势对NEP的影响在不同生态地理区差异较大。展开更多
文摘In this paper, a test system was developed in which a CCD camera was used as a sensor together with an IBM-AT-compatible computer with an Intel 80486 processor to measure the impurities and neps on a piece of cotton gray goods, and a method was proposed by which the differences of degree of gray between samples and interference caused by surface unevenness, creasing and the like within a test sample can be removed effectively. The whole test system is reliable, accurate and causing fewer subjective errors.
文摘Defect free yarn is a great demand for spinner, knitter, and weaver and also other textile personnel because numerous end products from knit apparels to woven fabrics, from towels to sheets and from carpets to industrial fabrics characteristics significantly depend on the physical properties of yarn. The qualities of rotor yarn are really directed by spinning parameters. The aim of this study is to observe the effect of spinning parameters such as rotor diameter and speed on thick, thin places and neps of yarn in rotor spinning process. 0.11 sliver hank of 100% cotton was used to produce 12 Ne yarn. 65% virgin cotton and 35% wastage cotton were mixed together. The positive impact of spinning parameters on yarn properties were accessed by thick places, thin places and neps. Results indicate that the yarn qualities were improved with increasing of rotor speed and rotor diameter. The rotor diameter was settled to 43 mm while rotor speed fluctuated from 35,000 to 45,000 rpm and rotor speed was fixed to 35,000 rpm while rotor diameter across contrasts from 43 mm to 66 mm.
文摘甘肃省草地是我国碳收支研究的关键区域,其净生态系统生产力(NEP)是衡量碳源/汇功能的核心。然而复杂的地形和气候条件导致该地区NEP估算存在较大不确定性。本研究基于集成生物圈模型(IBIS),模拟了1980—2022年甘肃省草地NEP的时空格局,并结合观测数据验证了模型精度。结果表明,IBIS模型能够较好地模拟该区域草地NEP动态(R^(2)=0.70,P<0.0001)。1980—2022年,甘肃省草地年均NEP为194.5 g m^(-2)·a^(-1)C,呈轻微上升趋势。年均NEP空间格局总体呈现东南高西北低,从东南向西北逐渐递减的趋势。南部草地大部分地区为碳汇区,北部部分干旱草原为碳源区,其NEP分布格局主要由降雨主导。本研究为甘肃省草地碳汇功能评估提供了科学依据,对实现区域“碳中和”目标具有重要参考价值。
文摘净生态系统生产力(NEP)是评价区域生态系统碳源碳汇的重要指标,厘清其时空分异格局及驱动机制对京津冀生态系统精准保护与修复至关重要.基于MODIS遥感数据估算了净生态系统生产力(NEP),采用Sen趋势+MK检验、Hurst指数和重心迁移等方法探究了京津冀2002~2020年固碳效益时空格局和演替规律,利用偏相关、复相关及残差分析定量解析了人类活动和气候变化驱动固碳效益时空分异的相对贡献.结果表明:①京津冀近20 a NEP呈逐年上升趋势,增长速率(以C计)为3.066 4g·(m^(2)·a)^(-1),空间上表现为西北高东南低;碳汇能力强的地区主要集中在张家口市和承德市周边,碳源效应强烈的区域分布在天津和邯郸等地;超过80%的区域碳汇能力呈上升趋势,其中极显著上升、显著上升区域占比分别为47.45%和8.29%,尤其是张-承地区,但未来增长趋势在逐步减缓;碳源重心在逐渐向东南部平原迁移,碳汇重心则由东北向西南迁移.②超过50%区域的NEP与年平均气温和年累计降水呈现正相关关系,但显著性均不强,复相关结果进一步证明了存在气象因素之外的其他条件在主导NEP的变化.③研究区域内NEP退化区与改善区占比分别为12.41%、87.59%,残差分析表明人类主导的固碳效益提升区占总改善区的94.88%,而退化区中气候主导的固碳效益降低区占62.84%,说明京津冀地区人类活动在影响生态系统固碳效益方面以正向促进为主.研究结论对精准识别京津冀生态系统保护与修复未来工作重心有指导意义.
文摘农田生态系统是陆地生态系统的重要组成部分,其碳源汇过程对气候变化的响应非常敏感。然而,当前气候变化及其碳氮耦合作用对农田生态系统碳源汇过程的影响贡献与驱动机制尚不明晰。基于总初级生产力(GPP)、净初级生产力(NPP)和净生态系统生产力(NEP)三种碳汇指标,以及系统总呼吸(Rs)、自养呼吸(Ra)和异养呼吸(Rh)三种碳源指标构建6种情景,揭示了中国农田生态系统碳源汇时空演变趋势特征,并基于Lindeman-Merenda-Gold(LMG)模型定量评估了气候变化及其碳氮耦合作用对中国农田生态系统碳源汇变化影响贡献。研究结果表明:(1)2000-2020年中国农田生态系统碳汇与碳源均表现为波动增长趋势,其中GPP、NPP和NEP平均增长率分别为4.27、1.65与0.15 g C m^(-2) a^(-1),Rs、Ra和Rh平均增长率分别为4.12、2.62与1.50 g C m^(-2) a^(-1),由于较高的呼吸作用,中国农田生态系统总体表现为弱碳汇;(2)2000-2020年中国农田生态系统除Rs/GPP以0.12%的速率小幅增长外,NEP/NPP、NEP/GPP及NEP/Rs均呈减少趋势,变化速率分别为-0.28%、-0.39%和-0.46%,呼吸主导作用逐渐加强导致碳汇主导作用减弱;(3)CO_(2)施肥和氮沉降对中国农田生态系统净碳汇增长的贡献为28.98%,主控了25.30%的农田碳汇区域。然而,CO_(2)施肥和氮沉降也导致了中国农田生态系统碳源增强,二者相对贡献率为32.41%,主控了26.75%的农田碳源区域。(4)GPP弱主导机制驱动了中国农田生态系统NEP的增长,GPP是碳汇区(KNEP>0)碳汇增长的主要驱动因子,主控了77.14%的农田碳汇区域。相反,Rs强主导机制导致了中国农田生态系统NEP下降,Rh是碳源区(KNEP<0)碳源增强的主要驱动因子,主控了46.98%的农田碳源区域。研究结果可为巩固提升农田生态系统碳汇,促进碳中和目标实现提供科学依据。
文摘旨在探索山东省及其子区域植被净生态系统生产力(Net Ecosystem Productivity,NEP)的时空变化特征及其驱动因素,评估气温(TEM)、降水(PRE)和饱和蒸汽压差(VPD)等因素对植被NEP的影响。基于2000-2020年间的植被净初级生产力(Net Primary Productivity,NPP),采用土壤呼吸地统计(Geostatistical Model of Soil Respiration,GSMSR)模型、植被NEP估算模型和地理探测器工具,通过趋势分析、相关分析和差异分析等研究方法,开展深入研究。结果表明,1)山东省植被NEP在2000-2020年间整体呈上升趋势,空间分布特征表现为从东北向西南递减,沿海地区高于内陆地区。全省植被NEP的年平均值为87.0 g·m^(-2)·a^(-1)(以C计),且超过1/3的地区由碳源区域转变为碳汇区域。2)山东省大部分地区植被NEP与气温、降水呈正相关,与饱和蒸汽压差呈负相关,不同因子间的交互作用普遍对植被NEP的影响大于单一因子的影响。3)山东省4个子区域(鲁西、鲁东、鲁北、鲁中南)植被NEP的变化趋势存在明显的空间分异,鲁中南地区植被NEP增加最为显著,其次是鲁西和鲁东地区,而鲁北地区的增幅相对较小。该研究为深入理解区域生态系统的碳循环动态以及制定相应的生态保护策略提供了科学依据。
文摘Teacher education at the foundational and preparatory stages plays a crucial role in shaping early childhood learning experiences.The National Curriculum Framework for School Education(NCFSE)2023 provides a structured pedagogical approach to address challenges in these stages.However,despite these policy frameworks,teachers in Kendriya Vidyalayas(KVs)continue to face numerous pedagogical challenges.This paper aims to explore and analyze the pedagogical challenges encountered by KV teachers in foundational and preparatory stage classrooms and compare them with the challenges addressed in NCFSE 2023.Using qualitative research methods,data were collected through structured online interviews with 10 KV teachers from different campuses.This paper investigated various challenges,including classroom management,language barriers,a lack of inclusive education strategies,insufficient infrastructure,limited parental involvement,and difficulties in integrating technology into teaching practices.The findings highlight the gap between policy recommendations and ground-level implementation.Based on these insights,the study suggests recommendations such as specialized teacher training,recruitment of special educators,improved infrastructure,enhanced parental engagement,and policy-driven interventions to bridge the gap between policy frameworks and real-world classroom experiences.The study concludes that addressing these challenges through targeted reforms can create a more inclusive and effective learning environment,fostering holistic student development at the foundational and preparatory stages.
基金supported by the National Natural Science Foundation of China(Grant No.52372260)the Science Fund for Distinguished Young Scholars of Hunan Province(Grant Nos.2024JJ2048 and 2021JJ10036)+1 种基金the Science and Technology Innovation Program of Hunan Province(Grant No.2022RC1197)the Scientific Research Fund of Hunan Provincial Education Department(Grant No.22B0512)。
文摘By combining neuroevolution potential(NEP)with phonon Boltzmann transport theory,we systematically investigate the thermal transport properties of three two-dimensional(2D)narrow bandgap semiconductors:Ca_(3)N_(2),Ba_(3)P_(2),and Ba_(3)As_(2).The room-temperature lattice thermal conductivities(κ_(L))of Ca_(3)N_(2),Ba_(3)P_(2),and Ba_(3)As_(2)considering only three-phonon scattering are 6.60 W/m K,11.90 W/m K,and 8.88 W/m K,respectively.When taking into account the higherorder phonon(four-phonon)scattering processes,theκL of these three materials decrease to 6.12 W/m K,9.73 W/m K and6.77 W/m K,respectively.Among these systems,Ba_(3)As_(2)undergoes the most pronounced suppression with a reduction of 23.8%.This is mainly due to the greater scattering phase space which enhances the four-phonon scattering.Meanwhile,it is revealed that unlike the traditional evaluation using the P_(4)/P_(3)ratio as an indicator of the strength of four-phonon interactions,the thermal conductivity of Ba_(3)P_(2)exhibits weaker four-phonon suppression behavior compared to Ba_(3)As_(2),despite hosting a higher P_(4)/P_(3)ratio.That is to say,the strength of four-phonon scattering cannot be evaluated solely by the ratio of P_(4)/P_(3).These results presented in this work shed light on the thermal transport properties of such new 2D semiconductors with narrow bandgaps.
文摘草地碳汇/源是植被生态系统中碳收支和碳平衡的一个重要内容,区分碳汇和碳源对气候变化的响应可为减源增汇提供科学依据。基于MODIS NPP数据和土壤呼吸模型量化了2001—2019年青藏高原草地净生态系统生产力(NEP)的时空变化和碳汇/源格局,利用通径分析方法分析了青藏高原气候变化对草地碳汇/源的影响。结果表明:青藏高原草地NEP呈现东高西低的分布格局,年平均值为54.41 g C m^(-2)。草地整体上以碳汇功能为主。碳汇区面积约为72.26万km^(2),碳源区面积约为47.82万km^(2),净碳汇总量65.35 Tg C a^(-1)。近19年青藏高原草地NEP以增加趋势为主,青藏高原气候暖湿化趋势有利于草地NEP的增加,增强碳汇;而暖干化趋势对NEP的影响在不同生态地理区差异较大。
