检索结果-内蒙古大学图书馆

Modified c p criterion for models with predicted responses as multiplication of a hat matrix

Procedia computer Science 2024年 246卷 1944-1953页

作者： Sanai Shibayama Koki Kirishima Hirokazu Yanagihara Mathematics Program Graduate School of Advanced Science and Engineering Hiroshima University 1-3-1 Kagamiyama Higashi-Hiroshima Hiroshima 739-8526 Japan

A risk function based on the standardized mean squared error of prediction is widely used for measuring the goodness of a model. However, using the risk function directly for model selection is generally not possible due to its inclusion of unknown parameters. The c p criterion is an asymptotic unbiased estimator of the risk function that has been commonly used in place of the risk function for model selection. Because the c p criterion can have a non-negligible bias against the risk function when the sample size is small, a modified c p criterion that completely corrects this bias was proposed by Fujikoshi and Satoh (1997) in a multivariate linear regression model. In this paper, we propose a modified c p criterion for common univariate models that generalize previous studies, i.e., the models in which the predicted response variables are defined as the product of a hat matrix and a vector of response variables.

关键词： geographically weighted regression hat matrix hyper-parameter selection modified c p penalized spline regression

来源：评论

学校读者我要写书评

暂无评论

An Ultrathin Microwave Metamaterial Absorber for c, X, and Ku Band Applications

引用

JOURNAL OF ELEcTRONIc MATERIALS 2021年第12期50卷 7275-7282页

作者： Elakkiya, A. Radha, S. Sreeja, B. S. Manikandan, E. Sri Sivasubramaniya Nadar Coll Engn Dept ECE Chennai 603110 Tamil Nadu India VIT Univ Sch SENSE Dept ECE Chennai Campus Chennai 600127 Tamil Nadu India

A five-band polarization-insensitive microwave metamaterial absorber (MMA) is discussed in this paper. The unit cell of the proposed MMA is composed of the top patch and a ground metallic plane, both separated by an FR4 dielectric substrate having an ultrathin thickness of 0.014 lambda. The proposed absorber structure offers five different absorption peaks at 5.4 GHz (c band), 8.7 GHz (X band), 14.53 GHz, 15.25 GHz, and 15.68 GHz (Ku band) with the absorptivity of 98%, 86%, 99%, 99.8%, and 99.9%, respectively, for both transverse electric (TE) and transverse magnetic (TM) modes. The analysis of the electric field, magnetic field, polarization, and angle independency has been performed to understand the absorption mechanism easily. The sensing behavior of the structure is analyzed by adding the analyte over the top metal layer. The microwave MMA has been fabricated and measured. The fabrication results agree with the simulation results. The design of the proposed absorber is expected to find application in explosive detection, sensing, defense, and airborne radar applications.

关键词： Microwave metamaterial absorber c X and Ku band sensing fabrication

来源：评论

学校读者我要写书评

暂无评论

Influence of preparation method on microstructure and tribological behavior of c/c-BN composites

引用

cERAMIcS INTERNATIONAL 2021年第9期47卷 12879-12896页

作者： Liu, Fuhai Yi, Maozhong Ran, Liping Ge, Yicheng Peng, Ke Cent South Univ State Key Lab Powder Met Changsha 410083 Peoples R China

In this study, with 2.5D needle punched carbon felt as reinforcement, hexagonal boron nitride (h-BN) was introduced through chemical vapor infiltration (cVI) and slurry impregnation (SI) methods, and then pyrocarbon was deposited through cVI to convert the BN-containing preform into carbon fiber reinforced carbon-boron nitride binary matrix composites (c/c-BN). The microstructure and mechanical properties of c/c-BN(P) composites prepared by SI combined with cVI were compared with those of c/c-BN(cVI) composites prepared by cVI. The tribological behavior of c/c-BN(P) composites containing different contents of h-BN fillers and c/c-BN (cVI) composites with and without heat treatment was investigated by the ball-on-disk technique in dry sliding conditions using Gcr15 steel balls and Si3N4 balls as sliding counterparts at two different sliding speeds (v = 0.2 and 0.8 m/s), and compared with the c/c composites used as a reference. c/c-BN(P) composites exhibit improved tribological behavior, which can be explained by the combined effect of SI and cVI on the microstructure and mechanical properties, leading to changes in the wear mechanism of the c/c-BN composites. The excellent reinforcement is attributed to the integrity structure of the c/c-BN(P), which can make the selflubricating friction layer stably exist on the surface of the material and significantly reduce the friction coefficient and wear loss of the c/c-BN(P) composite. Furthermore, the mechanical and tribological properties of c/cBN(P) composites can be adjusted by using different volume content of h-BN. The present work shows that c/cBN(P) composites have wide application prospects as anti-friction and wear-resistant materials.

关键词： c c-BN composites Microstructure Tribological behavior Friction Wear

来源：评论

学校读者我要写书评

暂无评论

Effects of c/N ratio on anaerobic co-digestion of cabbage, cauliflower, and restaurant food waste

引用

BIOMASS cONVERSION AND BIOREFINERY 2021年第5期11卷 2133-2145页

作者： Beniche, I. Hungria, J. El Bari, H. Siles, J. A. chica, A. F. Martin, M. A. Univ Ibn Tofail Kenitra Morocco Lab Renewable Energy & Environm Energy Biomass & Biogas Team Fac Sci BP 133 Kenitra 14000 Morocco Univ Cordoba Dept Chem Engn Campus Univ RabanalesCtra N-4Km 396 Cordoba 14071 Spain

Every day, a large amount of food waste (FW) is generated that causes serious environmental problems such as the production of greenhouse gases and leachate. A possible treatment for this waste is anaerobic digestion (AD), but there are several problems associated with the accumulation of volatile fatty acids (VFA), foaming, or low buffer capacity. In order to resolve or mitigate this problem, FW was mixed with cabbage and cauliflower (ccF) leaves and stalks at different carbon/nitrogen ratios (c/N) to add value to this agricultural waste and benefit from the advantages of co-digestion. Under the study conditions, promising results were obtained during the co-digestion of FW and agricultural wastes at c/N = 45. These include a high biodegradability (98%), a methane yield of 475 mL(STP) cH4/g VS, and an organic loading rate (OLR) of 0.06 kg of VS/m(3) h for the ccF and FW mixture (ccF + FW). Anaerobic co-digestion of ccF + FW might be an interesting option for the simultaneous treatment of these types of organic waste, with the consequent social and environmental benefits.

关键词： Food waste cabbage cauliflower Anaerobic co-digestion c N ratio

来源：评论

学校读者我要写书评

暂无评论

A new strategy of reusing abandoned carbon fiber reinforced plastic: Microstructures and properties of c/c composites based on recycled carbon fiber

引用

JOURNAL OF REINFORcED PLASTIcS AND cOMPOSITES 2021年第7-8期40卷 294-306页

作者： Guo, Wenjian Bai, Shuxin Ye, Yicong East China Jiao Tong Univ Inst Adv Mat Nanchang 330000 Jiangxi Peoples R China Natl Univ Def Technol Coll Aerosp Sci Changsha Peoples R China

A new strategy of recycling and reusing abandoned carbon fiber reinforced plastics (cFRP) is proposed: cFRPs are first fully carbonized to cF reinforced carbon (c/c) preforms, and then are manufactured into high value-added c/c composites. The results showed that the carbon residue rate of epoxy-resin (EP) matrix was fully recovered as the decomposition route of EP matrix was changed by charring agent. The recycled cF (rcF) was not markedly oxidized or thermally damaged, and possessed comparable properties with those of the virgin cF (vcF) after pyrolysis. The pyrolytic char had no obvious negative effect on the densification efficiency of the rcF reinforced carbon (rcF/c) composites. Both of the rcF/c and vcF reinforced carbon (vcF/c) composite bodies were quite dense, and exhibited almost no difference in their microstructures. The rcF/c and vcF/c composites therefore had quite close interface bonding strength (12.6 MPa and 13.0 MPa, respectively), and bending strength (106.4 MPa and 111.5 MPa, respectively). Furthermore, the rcF/c composites possessed comparable ablative rate with that of the vcF/c composites. The rcF/c composites derived from abandoned cF/EP composites present a great potential to be used as substitutes for vcF/c composites owing to their indistinguishable properties.

关键词： Recycling carbon fiber c c composites carbon fiber reinforced plastics

来源：评论

学校读者我要写书评

暂无评论

Na3V2(PO4)3/c composites as low-cost and high-performance cathode materials for sodium-ion batteries

引用

INTERNATIONAL JOURNAL OF ENERGY RESEARcH 2021年第3期45卷 4534-4542页

作者： Zhu, Limin Ding, Guochun Sun, Qiancheng Xie, Lingling cao, Xiaoyu Henan Univ Technol Sch Chem & Chem Engn Zhengzhou Peoples R China Henan Univ Technol Key Lab High Specif Energy Mat Electrochem Power Zhengzhou 450000 Peoples R China Henan Univ Technol Sch Environm Engn Zhengzhou Peoples R China

The carbon layer acting as a conductive medium is beneficial to overcoming the comparatively inferior electronic conductivity of Na3V2(PO4)(3). Based on this, Na3V2(PO4)(3)/c composites with diverse ratios of citric acid are synthetized via rheological phase reaction way in this work. The consequences display that the Na3V2(PO4)(3)/c-1.5 composite brings a higher initial discharge capacity of 113.2 mAh g(-1) at a current rate of 1 c with coulombic efficiency above 99% during all cycles. The discharge capacity retains at 117.6 mAh g(-1) at the 100th cycle. Even at the high current densities of 5 c and 10 c, the composite also shows superior cycling performance with negligible capacity fading. Its discharge capacities decline from 97 to 92.6 mAh g(-1) at 5 c and from 85.3 to 83.7 mAh g(-1) at 10 c. These remarkable outcomes arise from its preferable morphology with suitable carbon coating because both excess and skimpy carbon seriously affect the microstructure and electrochemical properties of Na3V2(PO4)(3)/c composites.

关键词： carbon coating cathode materials Na3V2(PO4)(3) c rheological phase reaction sodium‐ ion batteries

来源：评论

学校读者我要写书评

暂无评论

Experimental investigation on fatigue property at room temperature of c/Sic composites machined by rotary ultrasonic milling

引用

JOURNAL OF THE EUROPEAN cERAMIc SOcIETY 2021年第6期41卷 3341-3356页

作者： Xue, Feng Zheng, Kan Liao, Wenhe Shu, Jing Miao, Didi Nanjing Univ Sci & Technol Sch Mech Engn Nanjing 210094 Peoples R China

Rotary ultrasonic milling technology (RUM), as a surface strengthening machining method, was proposed to utilize in processing of c/Sic composites for enhancing anti-fatigue performance innovatively. Static tensile, intermittent fatigue and residual strength test were carried out. Due to constant impingement of high-frequency and low-amplitude vibration, surface residual compressive stress was formed near 2 GPa maximally. Axial thermal residual stress in fiber achieved -662.4 MPa proved by loading-unloading test. The peak value of fatigue damage parameter was reduced significantly. RUM surface restrains most of interface cracks because of residual compressive stress, and hinder the growth of fiber cracks for better machined surface quality. The damage accumulation, the first stress redistribution and fiber reinforcement stage were delayed. Average damage rate was decreased by 80.5 %. Residual tensile strength of RUM c/Sic was improved after fatigue, up to 95.8 % of tensile strength. The strengthening effect from RUM on fatigue property of c/Sic is significant and valuable.

关键词： Rotary ultrasonic milling c Sic composite Anti-fatigue performance Fatigue damage Residual stress

来源：评论

学校读者我要写书评

暂无评论

Development of-80 °c storage for Allium shoot tips using D cryo-plate method

引用

PLANT cELL TISSUE AND ORGAN cULTURE 2021年第1期144卷 115-122页

作者： Tanaka, Daisuke Sakuma, Yoshinori Yamamoto, Shin-ich Arizaga, Miriam Valle Niino, Takao Matsumoto, Toshikazu Natl Agr & Food Res Org Genet Resource Ctr Tsukuba Ibaraki Japan Univ Tsukuba Tsukuba Ibaraki Japan Shimane Univ Fac Life & Environm Sci Matsue Shimane Japan

D cryo-plate method was successfully adapted for storage at - 80 degrees c and - 196 degrees c of Allium shoot tips. The optimal D cryo-plate method using garlic shoot tips for the storage at - 80 degrees c and - 196 degrees c includes preculture of shoot tips for 2 days at 25 degrees c on solidified 1/2 MS medium containing 0.3 M sucrose, then placing them in wells on an aluminum cryo-plate, embedded in calcium alginate gel. Osmoprotection was performed by immersing the cryo-plates with shoot tips for 30 min at 25 degrees c in 2.0 M glycerol and 1.0 M sucrose. The optimal dehydration time of shoot tips was for 30 to 180 min at 25 degrees c. cooling was performed by transferring the samples on the cryo-plate into 2 ml cryotubes, then cooling into a deep freezer at - 80 degrees c for 14 days or directly plunging into liquid nitrogen (- 196 degrees c) for 60 min. The regrowth rate of shoot tips stored both at - 80 degrees c and - 196 degrees c was almost 100%. This optimized procedure was applied to seven Allium spp. The average regrowth rates after cooling at - 80 degrees c and - 196 degrees c were 95.3 and 94.0%, respectively. Thus, the storage of shoot tips at - 80 degrees c using D cryo-plate method is considered to be efficiently applicable for practical genebank storage. Key message D cryo-plate method was successfully adapted for storage at - 80 degrees c of Allium shoot tips. Grass transition temperature of shoot tips after air desiccation were - 39.4 degrees c.

关键词： Allium Aluminum plate D cryo-plate DSc Garlic Japanese shallot − 80 ° c Rakkyo

来源：评论

学校读者我要写书评

暂无评论

Effect of initial density on thermal conductivity of new micro-pipeline heat conduction c/Sic composites

引用

JOURNAL OF THE AMERIcAN cERAMIc SOcIETY 2021年第1期104卷 645-653页

作者： Zhang, Yunhai Liu, Yongsheng cao, Yejie cao, Liyang Wang, Jing Pan, Yu Wang, Ning Northwestern Polytech Univ Sci & Technol Thermostruct Composite Mat Lab Xian 710072 Peoples R China Natl Univ Def Technol Coll Aerosp Sci & Engn Sci & Technol Scramjet Lab Changsha 410073 Peoples R China

c/Sic composites prepared by chemical vapor infiltration technique (cVI) have been regarded as thermal structural materials widely. However, these composites still suffer from poor functional properties like low thermal conductivity, especially in thickness direction of the composites, limiting their large-scale applications. Herein, mesophase pitch based carbon fiber (MPcF) and continuous wave laser machining were utilized to construct highly effective heat conductive micro-pipelines within cVI c/Sic composite. The effect of initial density on the final density and thermal conductivity of the as-obtained MPcF-c/Sic composites were investigated. The results revealed that higher initial density would directly enhance the thermal conductivity and reduce the negative impact of the bottle-neck effect. At temperatures between 100 degrees c and 500 degrees c, MPcF-c/Sic composites preserved more than threefold of the thermal conductivity (340%) when compared to reference c/Sic composites. This work provides a highly effective route for enhancing the thermal conductivity of c/Sic, which would broaden their future applications.

关键词： c Sic composites heat conductive micro-pipelines initial density thermal conductivity

来源：评论

学校读者我要写书评

暂无评论

Influence of silicon infiltration on the wear and oxidation resistance of hot-pressed B4c/c(graphite) composites

引用

cERAMIcS INTERNATIONAL 2021年第24期47卷 34927-34939页

作者： Jiang, Tao Han, Manman Fu, Jia Xian Shiyou Univ Sch Mat Sci & Engn Xian 710065 Shaanxi Peoples R China

B4c/c(graphite) composites were produced using Hot-pressing. However, the composites exhibited low surface hardness, low wear resistance as well as low oxidation resistance. The hot-pressed B4c/c(graphite) composites were processed via silicon infiltration procedure at 1550 degrees c for 2 h in the vacuum condition to refine the wear resistance, surface hardness, and oxidation resistance of the B4c/c(graphite) composites. The silicon infiltration process resulted in the fabrication of a surface layer based on silicon carbide and silicon upon the B4c/c (graphite) composites surface. The surface layer of the silicon infiltrated B4c/c(graphite) composites, primarily comprising silicon carbide and silicon, was examined for its phase composition and microstructure. The oxidation resistance, wear resistance, and surface hardness of B4c/c(graphite) composites subjected to silicon infiltration was additionally examined. The XRD results confirmed that silicon carbide and silicon-based layer existed on the surface of B4c/c(graphite) composites, which was produced as a result of the silicon infiltration process. The surface of silicon infiltrated B4c/c(graphite) composites exhibited a 300-400 mu m thick covering of silicon carbide and silicon. The deposited layer also exhibited a dense and compact microstructure. When compared to hot-pressed B4c/c(graphite) composites, the surface hardness and wear resistance of the composites resulting after silicon infiltration were significantly enhanced. Silicon infiltrated B4c/c(graphite) composites possess a surface hardness of 16-17 GPa. The oxidation resistance of the silicon infiltrated B4c/c(graphite) composites was considerably enhanced as compared to the hot-pressed B4c/c(graphite) composites. So the silicon infiltrated B4c/c(graphite) composites exhibited high surface hardness, excellent wear resistance and excellent oxidation resistance in comparison with the hot-pressed B4c/c(graphite) composites.

关键词： A Hot pressing B composites c Hardness Wear resistance

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：