分类: 能源科学 >> 能源(综合) 提交时间: 2024-03-29
摘要: Considering the huge consumption of traditional energy and the rising demand for electricity, the development of renewable energy is very necessary. In this paper, an energy system integrating biomass energy, solar and two-stage organic Rankine cycle (ORC) is proposed, which uses the stable energy output of biomass energy to compensate for the volatility of solar modules. The proposed system comprises a biomass boiler, photovoltaic thermal panels (PV/T), evaporators, condensers, working medium pumps, turbines, a preheater and an air preheater. In addition, conventional and advanced exergy, exergoeconomic and exergoenvironmental (3E) analyses are carried out. Conventional 3E analyses reveal two components that require priority improvement. They are respectively evaporator 1 with the largest exergy destruction (708.2kW) and exergy destruction environmental impact rate (775.3 mPt/h) and evaporator 2 with the largest exergy destruction cost rate (19.15$/h). The results of advanced 3E analyses show that the largest avoidable endogenous exergy destruction is condenser 1 (136.6kW), the largest avoidable endogenous exergy destruction cost rate is condenser 2 (3.377$/h), and the largest avoidable endogenous exergy destruction environmental impact rate is condenser 1 (196.1mPt/h). These mean that these components have great potential for improvement in reducing exergy destruction, saving cost and protecting the environment. In addition, the avoidable endogenous exergy destruction/cost/environmental impact rate of evaporator 2 are negative, so evaporator 2 is not suitable as a priority component for improvement, which is contrary to the conclusions of conventional 3E analyses. It is found that conventional 3E analyses can only point out the biggest exergy destruction point, but cannot indicate whether the components with the greatest exergy destruction have the greatest potential for improvement. However, advanced 3E analyses can show the improvement potential of each component by improving its own performance and the external conditions. Therefore, it is necessary to conduct advanced 3E analyses.
分类: 心理学 >> 心理学其他学科 提交时间: 2024-03-28
摘要: 心理与脑科学以人类被试作为研究对象,其结果的可推广性(generalizability, 也称为普适性)很大程度上取决于其样本的代表性(representativeness)。但心理学与脑科学研究中样本的代表性长久以来受到诟病。当前研究中主要存在两大问题:(1) 样本信息的缺失,大部分研究仅报告了被试的性别、年龄与国别,而被试的种族/民族、受教育程度和社会经济地位等重要信息较少被报告,且从时间上看,这种状况未出现根本性改变;(2) 从已报告的信息来看,当前样本的代表性不足:女性被试多于男生,集中于西方的、年轻的和受过高等教育的人群,而中老年人、受教育水平较低人群及低收入人群较少被研究者关注,亚洲人/亚裔、黑人/非洲裔、西班牙裔/拉丁裔人群同样较少受到关注,从国别角度来说,亚非拉国家尤其是非洲、拉丁美洲与中东地区的人群较少出现在心理学和脑科学研究中。以上两大问题的产生可能主要存在如下原因:方便取样法作为主要的取样方法;欧美研究者主导了心理学与脑科学的研究;整体上忽视文化以及不同人口因素的影响;研究者自身存有偏见。要改变这种现状,需要研究者、学术组织、期刊编辑和基金资助方等多方的共同努力。提升样本代表性将有助于让心理学与脑科学的科学知识应用于更广泛的群体,推动人类命运共同体的构建。
分类: 能源科学 >> 能源(综合) 提交时间: 2024-03-28
摘要: With rapidly increasing consumption of energy, shipping industry has imposed a huge burden on the marine environment. It is a general trend to increase the use of renewable energy on ships to improve the ship sustainability. This article summarized the current development and application of solar energy, wind energy and fuel cell in ship power systems. Furthermore, in order to investigate the advantages of sustainable design for the ships, for the first time, a hybrid PV, wind and fuel cell energy system was established for an oil tanker, and the economic and environmental analyses of the hybrid system were performed. The analysis results demonstrate that the optimal hybrid energy system can reduce 151,467kg emission of CO2 and provide 2.92% electricity for the ship gird per year.
分类: 机械工程 >> 机械工程其他学科 提交时间: 2024-03-28
摘要: Increasing the transfer (HT) coefficient used in thermal industries is very important. Various methods are used to improve the efficiency of thermal heat HT so that maximum HT takes place in a smaller space. Ethylene glycol (EG) is generally used as an agent for convective HT. EG obtains energy from a hot source and discharges it to the required location. At present, the most consumption of EG is to produce engine cooling fluid. In the upcoming research, the TB of EG fluid in two-dimensional microchannels (MCs) has been investigated using molecular dynamics (MD) simulations, and the effect of variables such as MC dimensions and MC wall temperature (Temp) on the TB of the simulated fluid has been investigated. The results revealed that by increasing the Temp difference of the MC wall from 10 to 50 K, the maximum temperature (Max-Temp) and velocity (Max-Vel) of the target sample increased to 640.94 K and 0.024 Å/ps. It can be concluded that the increase in the cross-sectional area and the wall Temp difference leads to an increase in the HT rate in the MC.
分类: 心理学 >> 管理心理学 提交时间: 2024-03-28
摘要: 职场正念在人际领域的益处日渐凸显,有必要厘清其在概念发展和人际作用方面的新趋势,为组织塑造积极的职场环境提供启发。研究揭示目前存在两种不同的职场正念概念发展趋势:结果导向和过程导向,前者关注职场背景下概念与测量的统一趋势以探索有益的结果集合,后者侧重挖掘正念嵌入人际互动的过程机制;职场正念通过四种关联机制对质量和功能相关的人际结果产生影响:(1)在互动中通过开放的注意力捕捉信息以协调相互依赖工作的知识关联;(2)降低与内外部情绪体验相关的自我推断并强化与他人之间归属、支持和关怀的情感关联;(3)在互动中促进资源积累与抑制资源流失的资源关联;(4)导航资源流动方向与影响价值交换意愿的交换关联;资源和交换关联机制可辅助促进知识和情感关联机制。未来需更深入地探讨职场正念在数字化和AI 技术、远程办公及职场多样化、公平与包容性文化和污名化管理等挑战性工作领域的人际作用。
分类: 心理学 >> 发展心理学 分类: 心理学 >> 社会心理学 提交时间: 2024-03-28
摘要: 研究旨在考察影响人际情绪调节的关键因素。实验1采用情绪选择范式, 发现双方情绪一致时调节效果更好, 不一致时则优先调节负性情绪。同时, 策略匹配度仅在调节负性情绪时受到调节者情绪状态的影响。这可能是调节者分配部分认知资源于自我调节所致。因此, 实验2设置情绪一致情境的同时操纵调节者的注意资源, 发现仅在负性状态下, 关注自我组的人际调节效果更差, 策略匹配度更低。这就表明: (1)对负性事件的人际情绪调节效果优于正性事件。(2)人际情绪调节存在情绪一致性效应。(3)关注他人仅在调节负性情绪时能有效提高策略匹配度和调节效果。
分类: 数学 >> 离散数学和组合数学 提交时间: 2024-03-27
摘要: Let f(n) be the maximum number of edges in a graph on n vertices in which no two cycles have the same length. Erd¨os raised the problem of determining f(n). Erd¨os conjectured that there exists a positive constant c such that ex(n, C2k) ≥ cn1+1/k. Haj´os conjecture that every simple even graph on n vertices can be decomposed into at most n/2 cycles. We present the problems, conjectures related to these problems and we summarize the know results. We do not think Haj´os conjecture is true.
分类: 数学 >> 离散数学和组合数学 提交时间: 2024-03-27
摘要: The set of all non-increasing nonnegative integers sequence π = (d(v1), d(v2), ..., d(vn)) is denoted by NSn. A sequence π ∈ NSn is said to be graphic if it is the degree sequence of a simple graph G on n vertices, and such a graph G is called a realization of π. The set of all graphic sequences in NSn is denoted by GSn. A graphical sequence π is potentially H-graphical if there is a realization of π containing H as a subgraph, while π is forcibly H-graphical if every realization of π contains H as a subgraph. Let Kk denote a complete graph on k vertices. Let Km −H be the graph obtained from Km by removing the edges set E(H) of the graph H (H is a subgraph of Km). This paper summarizes briefly some recent results on potentially Km −G-graphic sequences and give a useful classification for determining σ(H, n).
分类: 计算机科学 >> 计算机应用技术 提交时间: 2024-03-27
摘要: 大语言模型 (LLMs, Large Language Models) 能够从大量语料的上下文中学习到模式,其包括词语之间的关系、句子的结构甚至更复杂的语义和语用信息。然而,让预训练语言模型生成结构化、严格遵循约定的内容仍然是一项挑战。我们提出了一种引导大模型生成计算机高可用内容的方案,无需微调和额外的神经网络推理,通过提前约定的上下文无关文法 (CFG, Context-Free Grammar) 构建一个采用协程的约束装置,在自回归模型Transformer的解码阶段引导模型采样正确的词元,以构成符合程序约定的形式语言。这将保证计算机程序每次都能把语言模型生成内容解析为期望的数据结构、类型或指令,以便开发人员更容易地将大语言模型纳入具体应用程序。我们在多个任务数据集上进行了实验,包括JSON、Mermaid框图和函数调用表达式生成等任务,结果表明我们的方法能够有效地提高LLMs生成内容对计算机程序的可用性。
分类: 物理学 >> 凝聚态:电子结构、电、磁和光学性质 提交时间: 2024-03-26
摘要: Under typical circumstances, it is commonly believed that solutions carrying a single type of charge are either non-existent or unstable. We have investigated the principles of high-concentration charged solution preparation techniques, employing methods such as electrostatic attraction, gravity separation, positive feedback, and self-powered mechanisms to effectively separate anions and cations in solution. Through electrostatic repulsion and the use of electrostatic separation networks, the partition of homoelectric ions has been achieved. Through water and electric separation, the capability for sustained accumulation of single-charge species has been attained, thus overcoming application bottlenecks and establishing evidence for the existence of charged solutions. We have proposed voltage limits and predicted phenomena such as electrostatic boiling, topological ice crystals, and strange ice crystals, thereby opening new perspectives and possibilities for enriching the understanding and research of electrostatics and electrochemistry. The introduction of the high-concentration charged solution and its controllable preparation are expected to facilitate or pioneer research in various fields including seawater desalination, wastewater treatment, hydrovoltaic power generation, and topological ice crystals, etc. This advancement holds the potential to rectify relevant discussions in textbooks. Implementing the dual electrostatic method for self-powered desalination and purification, coupled with wind, solar, and pumped hydro storage technologies, can aid in mitigating the intermittency and waste of wind and solar power, thus advancing the cause of seawater for land.
分类: 图书馆学、情报学 >> 图书馆学 提交时间: 2024-03-26
摘要: 图书馆学具有深厚的文化基因,在与文化互动共生的发展进程中彰显了专业价值。文章采用纵向分析、对比研究和归纳演绎等方法,从动因、基础和指向3个维度考察了中国图书馆学与文化互动的逻辑关系,梳理中国图书馆学与文化共生过程中面临的定位模糊、能力弱化和体系不全等主要问题。面向文化自信自强的学科发展环境和现实要求,应通过重塑学科制度、深挖知识基因、提升核心能力和增强影响力等策略,驱动并实现图书馆学价值的再发现。
分类: 数学 >> 离散数学和组合数学 提交时间: 2024-03-26
摘要: In 1975, P. Erd {o}s proposed the problem of determining the maximum number $f(n)$ of edges in a graph of $n$ vertices in which any two cycles are of different lengths. In this paper, it is proved that $$f(n) geq n+32t-1$$ for $t=27720r+169 , (r geq 1)$ and $n geq frac{6911}{16}t^{2}+ frac{514441}{8}t- frac{3309665}{16}$. Consequently, $ liminf sb {n to infty} {f(n)-n over sqrt n} geq sqrt {2 + {2562 over 6911}}.$
分类: 数学 >> 离散数学和组合数学 提交时间: 2024-03-26
摘要: In 1975,P.Erd {o}sproposedtheproblemofdeterminingthemaximumnumber$f(n)$ofedgesinagraphwith$n$verticesinwhichanytwocyclesareofdifferentlengths.Inthispaper,itisprovedthat$$f(n) geqn+ frac{107}{3}t+ frac{7}{3}$$for$t=1260r+169 , (r geq1)$and$n geq frac{2119}{4}t^{2}+87978t+ frac{15957}{4}$.Consequently,$ liminf sb{n to infty}{f(n)-n over sqrtn} geq sqrt{2+ frac{7654}{19071}},$whichisbetterthanthepreviousbounds$ sqrt2$ Y.Shi,DiscreteMath.71(1988),57-71 ,$ sqrt{2.4}$ C.Lai,Australas.J.Combin.27(2003),101-105 .Theconjecture$ lim_{n rightarrow infty}{f(n)-n over sqrtn}= sqrt{2.4}$isnottrue.
分类: 数学 >> 离散数学和组合数学 提交时间: 2024-03-26
摘要: 设f(n) 是没有等长圈的n个顶点的图的最大可能边数。确定f(n)的问题由Erdos在1975年提出。本文给出了f(n)的下界。
分类: 动力与电气工程 >> 工程热物理学 提交时间: 2024-03-26
摘要: We conduct an experimental investigation on the integration of film cooling for thermal protection in a 72-mm cylindrical rotating detonation engine (RDE). The cooling scheme employs the injection of cooling air through a series of cat-ear-shaped film cooling holes densely distributed along the outer wall of the cylindrical combustor. Our findings reveal successful initiation of the RDE and sustained propagation of the rotating detonation wave (RDW) when film cooling is activated.
分类: 核科学技术 >> 粒子加速器 提交时间: 2024-03-25
摘要: 光核反应和紧凑型中子源是生产医用同位素的新兴工具,东华理工大学(ECUT)正在建设一种电子加速器驱动的光中子源(ECANS),用于医用同位素生产研究。本文在分析W- 100Mo光中子源的中子产额及99Mo产量的基础上,建立了中子能量调节层和中子反射层组成的放射性同位素产生模型,对不同天然氧化物材料(MoO3、Lu2O3、Y2O3)进行了放射性同位素的产生模拟及伴生产物分析,探讨了光核反应中子源生产医用同位素的可行性。研究结果显示,在高富集100Mo靶材中99Mo同位素的产量为54.1 Ci/day,在氧化物靶材中99Mo的产量为17.4 Ci/day、177Lu的产量为18.2 Ci/day以及90Y的产量为57.0 Ci/day。此外分析了天然氧化物在辐照条件下放射性杂质的含量,为后续分离纯化提供数据参考。
分类: 物理学 >> 核物理学 提交时间: 2024-03-22
摘要: 介子束流与原子核碰撞实验在中高能核物理和粒子物理研究领域发挥了重要推动作用,特别是在强子谱研究方面取得了一系列重要实验测量结果。本文对目前国际上几个比较典型的介子束流实验进行了梳理与总结,这包括了位于日本的 J-PARC 实验;欧洲核子中心的 COMPASS 实验、AMBER 实验以及计划中的 HIKE实验;美国 JLab 的 GlueX 实验和 EIC 项目。进一步,我们基于国内的 HIAF 装置对可能产生的次级介子束流的参数指标进行了分析估算,并讨论了可以开展的相关物理测量。通过对这些实验项目的调研分析,旨在为进一步规划和建造我国的介子束流实验装置并开展强子物理方面的研究有所启发和借鉴。
分类: 物理学 >> 核物理学 提交时间: 2024-03-19
摘要: The exploration of exotic shapes and properties of atomic nuclei, e.g., α cluster and toroidal shape, is afascinating field in nuclear physics. To study the decay of these nuclei, a novel detector aimed at detectingmultiple alpha-particle events was designed and constructed. The detector comprises two layers of double-sidedsilicon strip detectors (DSSD) and a cesium iodide scintillator array coupled with silicon photomultipliers arrayas light sensors, which has the advantages of their small size, fast response, and large dynamic range. DSSDscouple with cesium iodide crystal arrays are used to distinguish multiple alpha hits. The detector array has acompact and integrated design that can be adapted to different experimental conditions. The detector array wassimulated using Geant4, and the excitation energy spectra of some alpha-clustering nuclei were reconstructedto demonstrate the performance. The simulation results show that the detector array has excellent angularand energy resolutions, enabling effective reconstruction of the nuclear excited state by multiple alpha particleevents. This detector offers a new and powerful tool for nuclear physics experiments and has the potential todiscover interesting physical phenomena related to exotic nuclear structures and their decay mechanisms
分类: 物理学 >> 核物理学 提交时间: 2024-03-19
摘要: In recent years, the gap between the supply and demand of medical radioisotopes has increased, necessitating new methods for producing medical radioisotopes. Photonuclear reactions based on gamma sources have unique advantages in terms of producing high specific activity and innovative medical radioisotopes. However, the lack of experimental data on reaction cross sections for photonuclear reactions of medical radioisotopes of interest has severely limited the development and production of photonuclear transmutation medical radioisotopes. In this study, the entire process of the generation, decay, and measurement of medical radioisotopes was simulated using online gamma activation and offline gamma measurements combined with a shielding gammaray spectrometer. Based on a quasi-monochromatic gamma beam from the Shanghai Laser Electron Gamma Source (SLEGS), the feasibility of the measurement of production cross section for surveyed medical isotopes was simulated, and specific solutions for measuring medical radioisotopes with low production cross sections were provided. The feasibility of this method for high precision measurements of the reaction cross section of medical radioisotopes was demonstrated.
分类: 物理学 >> 核物理学 提交时间: 2024-03-19
摘要: 重离子碰撞过程中轻粒子的产生对于提取核物质状态方程的信息有着重要的作用。基于极端相对论量子分子动力学(UrQMD)模型,利用统计衰变模型GEMINI++处理预激发碎片的衰变,研究了预碎片的衰变对中能区Au+Au碰撞过程中轻粒子的集体流和核阻止本领的影响。研究发现,由于记忆效应,重离子碰撞过程中的预碎片的衰变产生的子核继承了母核的部分动力学性质,在考虑预碎片的衰变后可以更好地描述实验数据,并且这种效应对观测量的影响随碰撞能量的升高而减弱。结果表明,重离子碰撞过程中预碎片的衰变以及轻粒子的产生对敏感于核物质状态方程的观测量有着一定的影响。在利用这些观测量提取核物质状态方程的信息时应当仔细处理。