Ionic thermal up-diffusion in nanofluidic salinity-gradient energy harvesting

Advances in nanofabrication and materials science give a boost to the research in nanofluidic energy harvesting. Contrary to previous efforts on isothermal conditions, here a study on asymmetric temperature dependence in nanofluidic power generation is conducted. Results are somewhat counterintuitive. A negative temperature difference can significantly improve the membrane potential due to the impact of ionic thermal up-diffusion that promotes the selectivity and suppresses the ion-concentration polarization, especially at the low-concentration side, which results in dramatically enhanced electric power. A positive temperature difference lowers the membrane potential due to the impact of ionic thermal down-diffusion, although it promotes the diffusion current induced by decreased electrical resistance. Originating from the compromise of the temperature-impacted membrane potential and diffusion current, a positive temperature difference enhances the power at low transmembrane-concentration intensities and hinders the power for high transmembrane-concentration intensities. Based on the system''s temperature response, we have proposed a simple and efficient way to fabricate tunable ionic voltage sources and enhance salinity-gradient energy conversion based on small nanoscale biochannels and mimetic nanochannels. These findings reveal the importance of a long-overlooked element—temperature—in nanofluidic energy harvesting and provide insights for the optimization and fabrication of high-performance nanofluidic power devices.     

数字化能源管理系统促进工业界节能减碳的分析与建议

工业生产是碳排放的主要来源。减少能源浪费、达成生产节能对实现我国“双碳”目标至关重要。随着数字化技术进步,数字化能源管理系统可通过将不可见的能源可视化,促进企业节能。文章分析了英国、美国、德国、日本和瑞典应用能源管理系统的现状,总结了其特点与应用条件,与我国在此方面的发展进行了对比,并探讨了我国在部署能源管理系统过程中所面临的挑战。文章还提出从“工厂、产线和设备”到“产品”角度分析能耗,构建“基于生产步骤的单位产品能耗标签”的方法论框架。探讨了政府、企业等利益相关者在该方法论中的角色,并提出了政府支持发展数字化能源管理系统的对策,包括推动系统建设、支持合作、确定能耗基准和引导企业对标行业最优实践。     

Light-driven directional ion transport for enhanced osmotic energy harvesting

Light-driven ion (proton) transport is a crucial process both for photosynthesis of green plants and solar energy harvesting of some archaea. Here, we describe use of a TiO₂/C₃N₄ semiconductor heterojunction nanotube membrane to realize similar light-driven directional ion transport performance to that of biological systems. This heterojunction system can be fabricated by two simple deposition steps. Under unilateral illumination, the TiO₂/C₃N₄ heterojunction nanotube membrane can generate a photocurrent of about 9 μA/cm², corresponding to a pumping stream of ∼5500 ions per second per nanotube. By changing the position of TiO₂ and C₃N₄, a reverse equivalent ionic current can also be realized. Directional transport of photogenerated electrons and holes results in a transmembrane potential, which is the basis of the light-driven ion transport phenomenon. As a proof of concept, we also show that this system can be used for enhanced osmotic energy generation. The artificial light-driven ion transport system proposed here offers a further step forward on the roadmap for development of ionic photoelectric conversion and integration into other applications, for example water desalination.     

Secrecy analysis for IoT relaying networks deploying NOMA with energy harvesting

In this paper, we investigate the physical-layer security for an Internet of Things (IoT) relaying network employing non-orthogonal multiple access (NOMA) in the context of non-linear energy harvesting. In particular, a power-constrained source transmits its confidential information to a destination via an IoT device, which first decodes the received signal and then forwards the decoded data together with its own information using the NOMA technique to their respective destinations, while an eavesdropper is overhearing this transmission. Considering the scenario that both the power-constrained source and the IoT device are assumed to work under non-linear energy harvesting modes, and are capable of harvesting energy from a power beacon with a time switching protocol, both analytical and asymptotic expressions for secrecy outage probability as well as the analytical expression for the probability of strictly positive secrecy capacity are derived. In addition, those expressions are also verified with Monte-Carlo simulations.     

Bond graphs for thermal energy transport and entropy flow

The transport of thermal energy in thermodynamics is described as the product of entropy flow and of the absolute temperature, in analogy to the volume flow and pressure in oil hydraulics and to electric charge flow (= current) and voltage in electronics. Bond graphs are shown to be especially suitable to describe the splitting of applied thermal energy into internal energy and external mechanical work. Transformers and the 0- and 1-junctions of Paynter can illustrate various entropy flow processes, including Carnot engines and heat exchangers. Entropy flow in heat conduction is distinguished from entropy convection, or transport by moving mass, where the entropy/temperature characteristic or equation of state is important. Irreversibilities are represented by impedance transformers reducing temperature and increasing entropy flow but conserving power.     

孙疃-赵集勘探区现今地温场特征及其高温热害预测

淮北煤田是中国东部主要的煤炭生产基地之一.通过分析淮北煤田孙疃-赵集2个新勘探矿区中测温数据资料,绘制出了研究区主采煤层在后期开采中可能产生高温热害的分布图.研究表明:孙疃-赵集勘探区现今地温梯度分布范围介于1.7 ～3.6℃/hm,平均现今地温梯度约为2.68℃/hm,3个主采煤层的高温热害区表现出了东高西低的特点.     

可再生能源——氢能的发展与化石能源的替代

一、能源问题的重要性 能源是人类生存和发展的重要物质基础,也是当今国际政治、经济、军事外交关注的焦点,经济社会持续快速发展．离不开有利的能源保障。     

The thermal conductivity of the Earth's core and implications for its thermal and compositional evolution

The thermal conductivity of iron alloys is a key to understanding the mechanism of convection in the Earth's liquid core and its thermal history.The Earth's mag...     

A microfluidic device for uniform-sized cell spheroids formation,culture, harvesting and flow cytometry analysis

Culture of cells as three-dimensional (3D) aggregates, named spheroids, possesses great potential to improve in vitro cell models for basic biomedical research. However, such cell spheroid models are often complicated, cumbersome, and expensive compared to conventional Petri-dish cell cultures. In this work, we developed a simple microfluidic device for cell spheroid formation, culture, and harvesting. Using this device, cells could form uniformly sized spheroids due to strong cell–cell interactions and the spatial confinement of microfluidic culture chambers. We demonstrated cell spheroid formation and culture in the designed devices using embryonic stem cells, carcinoma cells, and fibroblasts. We further scaled up the device capable of simultaneously forming and culturing 5000 spheroids in a single chip. Finally, we demonstrated harvesting of the cultured spheroids from the device with a simple setup. The harvested spheroids possess great integrity, and the cells can be exploited for further flow cytometry assays due to the ample cell numbers.     

技术进步对中国火力发电部门要素偏向与能源强度的影响

在碳达峰、碳中和的背景下,中国电力部门的碳减排一方面依赖于能源结构的优化,另一方面也需要火力发电部门能源强度的降低。本文基于中国火力发电企业层面数据,在超越对数成本函数的框架中纳入企业研发投入、外商直接投资、环境规制3种技术进步来源,采用似不相关回归法估计成本函数系数,进而估算要素替代弹性,分析不同来源技术进步对要素投入及能源强度的影响,讨论技术进步的要素偏向性。研究结论发现：①企业研发投入、外商直接投资的技术溢出效应带来显著的中性技术进步和要素节约,均对能源强度下降有显著贡献;相较于东部企业和大型企业,中西部企业、小型企业的技术进步效应较弱。②环境规制主要通过设备更新等直接效应实现能源偏向性技术进步,而通过企业研发投入的间接机制实现技术进步的影响并不显著。因此,有必要通过促进创新成果推广应用、建设区域间企业交流合作平台、完善环境规制政策组合等措施,激励不同来源技术进步对中国火力发电行业能源要素节约、能源强度下降的作用。     

一种由需求驱动的信息技术创新与扩散政策生成体系

分析了信息技术创新扩散的因果关系。认为 ,IT市场的信息不完全性、市场结构、信息技术网络外特性 ,是决定信息技术创新扩散的原因。针对传统的、单一的以信息技术R&D为目标的IT政策 ,或单一的面向扩散的信息技术政策 ;提出了一种由信息技术市场需求驱动的、协调信息技术供应商、信息技术潜在接受者、信息技术政策决策者关系的IT政策产生系统及其输出 ,其目的在于调节信息技术扩散速率 ,使其达到Pareto意义下的最优扩散路径 ,并详细地分析了该信息技术政策体系的结构与原理。     

锂原子能级和光学振子强度的相对论性理论研究

应用相对论多通道理论,计算锂原子1s2ns2S,1s2np2P,1s2nd 2D和1s2nf2F系列束缚态和相邻连续态的本征量子数亏损,并拟合得到量子亏损函数,进而计算1s2np2P系列n=7 ～60的电离能和量子数亏损,计算结果与最新的实验值相符合.采用相对论多组态相互作用方法计算锂原子1s22s→1s2np1/2偶极跃迁光学振子强度,结果表明,通过包含单、双电子激发组态考虑电子关联作用,计算结果有很大的改善.     

A data-driven subspace predictive control method for air-cooled data center thermal modelling and optimization

This paper presents a data-driven predictive control method for optimizing the energy consumption of air-cooled data centers with unknown system model parameters. First, based on the measurable data of the studied system, the subspace predictive control (SPC) method is adopted to improve the energy use efficiency of the data center by regulating the power allocation of the server racks and the supply temperature of cold air, while ensuring the safe operating environment of the electronic equipment. Furthermore, a reasonable event-triggered law is designed to solve the problem of the low computational efficiency of the conventional SPC method. The simulation results illustrate that the designed event-triggered law can improve the computational efficiency of the algorithm while maintaining the control performance of the algorithm, which verifies its application prospect in practice.     

一种提升吞吐量与能量效率的LTE/WLAN两跳中继网络

LTE系统能够提供更高的数据速率,然而小区边缘用户由于受到严重的小区间干扰以及较大的路径损耗,其吞吐量比小区中心用户差.对于相同的发射功率,小区边缘用户较低的吞吐量导致整个系统的能量效率较低.针对LTE 3扇区场景,提出一种基于LTE/WLAN的两跳中继网络架构,用于提高小区边缘用户的吞吐量,以及LTE系统的能量效率.理论分析和仿真结果表明,新型网络在用户吞吐量以及系统能量效率方面均有显著提升.     

浅谈新能源发电给生产和生活带来的影响

在21世纪的今天,随着经济、文化、政治等的发展,世界能源结构也在不断的发生改变。人们亟待解决一次能源的大量消耗导致全球能源短缺和气候恶化等问题。新型能源,如太阳能、风能、地热能、潮汐能、生物质能等能源的出现使得能源短缺的部分问题得到了解决,地球的生态环境得以改善,给人们的生产生活提供极大便利。     

Distributed fusion filtering for multi-sensor systems under time-correlated fading channels and energy harvesters

In this paper, the distributed fusion filtering issue is investigated for multi-sensor systems with the constraints from both time-correlated fading channels and energy harvesters. A specific scenario is considered where the sensors can harvest energy from the natural environment and may consume a certain amount of energy when transmitting measurements to the filters. In order to properly deal with the energy supply relationship between a battery and multiple sensors, a dynamic energy-allocated rule is proposed in this paper, i.e., the storage battery provides energy to sensors in order of different sensors’ priorities. Additionally, the channel fading phenomenon is also taken into consideration and the fading coefficient is described by a dynamic process. In this paper, we are committed to designing a local filter such that, under the effects of the time-correlated fading channels and energy harvesters, an upper bound on the local filtering error covariance is firstly derived by using the mathematical induction and then the upper bound is minimized by designing the local filter gain. Next, the covariance intersection approach is employed to obtain the fusion estimates. Finally, a simulation is provided to verify that the presented filtering strategy is feasible and effective.     

S＆T advisors call for development of petroleum supplements and alternative energy sources in China

Under the auspices of the Academic Divisions of CAS (CASAD), a panel of experts recently completed a consultative project on the medium- and long-term development strategy for petroleum supplements and alternative energy sources in China.