Revealing the solid-state reaction process among multiphase multicomponent ceramic during ablation

Multiphase design is a promising approach to achieve superior ablation resistance of multicomponent ultra-high temperature ceramic,while understanding the ablation mechanism is the foundation.Here,through investigating a three-phase multicomponent ceramic consisting of Hf-rich carbide,Nb-rich carbide,and Zr-rich silicide phases,we report a newly discovered solid-state reaction process among multiphase multicomponent ceramic during ablation.It was found that this solid-state reaction occurred in the matrix/oxide scale interface region.In this process,metal cations are counter-diffused between the multicomponent phases,thereby resulting in their composition evolution,which allows the multicomponent phases to exist stably under a higher oxygen partial pressure,leading to the improvement of thermodynamic stability of three-phase multicomponent ceramic.Additionally,this solid-state reaction process appears synergistic with the preferential oxidation behavior among the oxide scale in enhancing the ablation performance.

Assessment of Municipal Solid Waste Management in the Farmgate Area of Dhaka North City Corporation

This investigation is focused on conducting a thorough analysis of Municipal Solid Waste Management (MSWM). MSWM encompasses a range of interdisciplinary measures that govern the various stages involved in managing unwanted or non-utilizable solid materials, commonly known as rubbish, trash, junk, refuse, and garbage. These stages include generation, storage, collection, recycling, transportation, handling, disposal, and monitoring. The waste materials mentioned in this context exhibit a wide range of items, such as organic waste from food and vegetables, paper, plastic, polyethylene, iron, tin cans, deceased animals, byproducts from demolition activities, manure, and various other discarded materials. This study aims to provide insights into the possibilities of enhancing solid waste management in the Farmgate area of Dhaka North City Corporation (DNCC). To accomplish this objective, the research examines the conventional waste management methods employed in this area. It conducts extensive field surveys, collecting valuable data through interviews with local residents and key individuals involved in waste management, such as waste collectors, dealers, intermediate dealers, recyclers, and shopkeepers. The results indicate that significant amounts of distinct waste categories are produced daily. These include food and vegetable waste, which amount to 52.1 tons/day;polythene and plastic, which total 4.5 tons/day;metal and tin-can waste, which amounts to 1.4 tons/day;and paper waste, which totals 5.9 tons/day. This study highlights the significance of promoting environmental consciousness to effectively shape the attitudes of urban residents toward waste disposal and management. It emphasizes the need for collaboration between authorities and researchers to improve the current waste management system.

四L悬浮导向分开支承型直线进给单元模态分析

介绍了一种自行设计的四L悬浮导向分开支承型直线进给单元的机械结构和工作原理,研究了单自由度磁悬浮支承系统的数学模型,建立了五自由度磁悬浮直线进给单元的振动模型。借助ANSYS软件对四L悬浮导向分开支承型直线进给单元进行模态分析,计算出该直线进给单元的多阶固有频率和振型,并分析了电磁铁的磁悬浮支承的刚度和阻尼对四L悬浮导向分开支承型直线进给单元固有频率的影响。计算分析可用于指导机床用磁悬浮直线进给单元结构的优化设计。

High entropy fluorides as conversion cathodes with tailorable electrochemical performance

With the recent development of high entropy materials, an alternative approach to develop advanced functional materials with distinctive properties that show improved values compared to conventional materials has been provided. The high entropy concept was later successfully transferred to metal fluorides and high entropy fluorides(HEFs) were successfully synthesized. Owing to their high theoretical specific capacities in energy storage applications, HEFs were utilized as cathode materials for lithiumion batteries(LIBs) and their underlying storage mechanisms were investigated. Instead of a step-bystep reduction of each individual metal cation, the HEFs seem to exhibit a single-step reduction process,indicating a solid solution compound instead of merely a mixture of different metal fluorides. It was also observed that the electrochemical behavior of the HEFs depends on each individual incorporated element. Therefore, by altering the elemental composition, new materials that exhibit improved electrochemical properties can be designed. Remarkably, HEFs with seven incorporated metal elements exhibited a better cycling stability as well as a lower hysteresis compared to binary metal fluorides.These findings offer new guidelines for material design and tailoring towards high performance LIBs.

Multiple forest structural elements are needed to promote beetle biomass, diversity and abundance

Background:Retention forestry is a management strategy aiming to mitigate biodiversity loss by retaining structural elements such as dead trees that would otherwise be removed.Here we analyze the biomass,diversity and abundance among forest beetles collected using window traps on 1281-ha forest sites reflecting gradients in the amount of structural elements in southwestern Germany.Results:We found that beetle biomass increased with mean diameter at breast height(a measure of tree size),and decreased with stand structural complexity.Biomass of individual feeding guilds responded differently to forest structural elements,namely lying deadwood,understory complexity,tree basal area and stand structural complexity.Beetle family diversity increased with the effective number of layers,i.e.1-m forest strata occupied by vegetation assessed via terrestrial laser scanning.Abundance of feeding guilds responded to only elevation and share of deciduous trees.Community composition in terms of biomass was structured by forest elements similar to biomass of individual feeding guilds,with the addition of lying deadwood.This differed from community composition in terms of abundance of feeding guilds,which was structured by primarily standing deadwood volume and share of deciduous trees.Conclusions:Our results show that biomass,diversity and abundance respond differently to forest structural elements.This suggests that the concurrent prioritization of multiple forest elements is needed to promote forest beetles,with more focus placed on the differing resource needs among feeding guilds.In addition,retention strategies should also consider the varying responses of beetle biodiversity metrics when assessing the importance of forest structural elements.

Perovskites for Laser and Detector Applications

Perovskite materials have triggered a renewed interest in photovoltaic research in the recent years.They display crystal forms with 0D,1D and 2D,3D motifs,and several chemical forms,namely inorganic(titanates,rubidiates,nobiates,tantalates etc.),organic/inorganic metal halides with single to multiple cations,and even organic polymer or quantum dot-infused hybrids.Each crystal type and chemical form are endowed with specific physicochemical,optical,electronic,and morphological properties.These unique properties render them suitable for targeted applications,namely photovoltaics,LEDs,photocatalysis/electrolysis/solar fuels/solar and Li-ion batteries,gas-sensors,ferroelectrics,capacitors,transistors and memristors,photodetectors,and lasers,for advanced quantum cryptography and outer space applications.At first,the crystal and material types,and physicochemical,morphological,and optoelectronic properties of perovskite materials are discussed.Particularly,we focus on those properties which cumulatively contribute to their application in the abovementioned fields.Simultaneously,a comprehensive discussion about the advances in each field is presented.Structure/property/application relationships with key advances demonstrate the versatility of perovskites in modern optoelectronic technologies.

Zr−Co−Ge三元体系在1023、1173和1373 K条件下的相平衡

采用合金法并结合电子探针显微分析(EPMA)和X射线衍射(XRD)技术,精确测定Zr−Co−Ge三元体系在1023、1173和1373 K条件下的相平衡。合理构建Zr−Co−Ge体系在1023、1173和1373 K条件下的等温截面,分别包含29、28和26个三相区。除了证实文献中报道的5个三元化合物外,还检测到一个具有显著均匀性范围的新三元相τ,其组成在1023 K时为13.8%~19.4%Co(摩尔分数),在1173 K时为12.9%~19.0%Co(摩尔分数)和在1373 K时为12.3%~14.9%Co(摩尔分数)。而且,推断一个零变量反应发生在1023~1173 K,即τ+τ1τ4+ZrGe2。此外,第三种元素Ge在一些Co−Zr中间相中可以部分替代Co,如CoZr2和Co23Zr6,其中,Ge的最大溶解度分别可达22.8%和20.3%(摩尔分数)。

Polymer-/Ceramic-based Dielectric Composites for Energy Storage and Conversion

Dielectric composites boost the family of energy storage and conversion materials as they can take full advantage of both the matrix and filler.This review aims at summarizing the recent progress in developing highperformance polymer-and ceramic-based dielectric composites,and emphases are placed on capacitive energy storage and harvesting,solid-state cooling,temperature stability,electromechanical energy interconversion,and high-power applications.Emerging fabrication techniques of dielectric composites such as 3D printing,electrospinning,and cold sintering are addressed,following by highlighted challenges and future research opportunities.The advantages and limitations of the typical theoretical calculation methods,such as finite-element,phase-field model,and machine learning methods,for designing high-performance dielectric composites are discussed.This review is concluded by providing a brief perspective on the future development of composite dielectrics toward energy and electronic devices.

Observation of a highly conductive warm dense state of water with ultrafast pump–probe freeelectron-laser measurements

The electrical conductivity of water under extreme temperatures and densities plays a central role in modeling planetary magnetic fields.Experimental data are vital to test theories of high-energy-densitywater and assess the possible development and presence of extraterrestrial life.These states are also important in biology and chemistry studies when specimens in water are confined and excited using ultrafast optical or free-electron lasers(FELs).Here we utilize femtosecond optical lasers to measure the transient reflection and transmission of ultrathin water sheet samples uniformly heated by a 13.6 nm FEL approaching a highly conducting state at electron temperatures exceeding 20000 K.The experiment probes the trajectory ofwater through the high-energy-density phase space and provides insights into changes in the index of refraction,charge carrier densities,andACelectrical conductivity at optical frequencies.At excitation energy densities exceeding 10MJ/kg,the index of refraction falls to n0.7,and the thermally excited free-carrier density reaches ne531027 m−3,which is over an order of magnitude higher than that of the electron carriers produced by direct photoionization.Significant specular reflection is observed owing to critical electron density shielding of electromagnetic waves.Themeasured optical conductivity reaches 23104 S/m,a value that is one to two orders of magnitude lower than those of simplemetals in a liquid state.At electron temperatures below 15000 K,the experimental results agreewell with the theoretical calculations using density-functional theory/molecular-dynamics simulations.With increasing temperature,the electron density increases and the system approaches a Fermi distribution.In this regime,the conductivities agree better with predictions from the Ziman theory of liquid metals.

Delphi-Based Planning Approach in the Maritime Transport Chain

The objective of this paper is to illustrate behavioural aspects and a collaborative Delphi-based planning approach in the maritime transport chain. Therefore, this paper analyses changes in behavioural routines and governance structures in the maritime transport chain using a case study that depicts mutual projections of expected container transhipment moderated by a neutral third for reducing the uncertainty in planning within the whole maritime transport chain. The actors＇ different views on container transport are collected and directly confronted to an expert panel showing bounded rationality and thus asymmetric information can be circumvented The planning approach shows how actors＇ different internal planning can be improved and evident to the market. The whole maritime transport chain expects the future development in container transport which can be given by using collaborative Delphi-based planning. As a result, an overall picture for planning issues can be constituted, improving both individual planning of the actors and expected market growth.

Correlating the electronic structure of perovskite La_(1-x)SrxCoO_(3) with activity for the oxygen evolution reaction:The critical role of Co 3d hole state

Perovskite LaCoO_(3) is being increasingly explored as an effective low-cost electrocatalyst for the oxygen evolution reaction(OER).Sr doping in LaCoO_(3)(La1-xSrxCoO_(3))has been found to substantially increase its catalytic activity.In this work,we report a detailed study on the evolution of the electronic structure of La1-xSrxCoO_(3) with 0≤x≤1 and its correlation with electrocatalytic activity for the OER.A combination of X-ray photoemission spectroscopy(XPS)and X-ray absorption spectroscopy(XAS)was used to unravel the electronic density of states(DOS)near the Fermi level(EF),which provide insights into the key electronic structure features for the enhanced OER catalytic activity.Detailed analysis on the Co L-edge XAS suggest that LaCoO_(3) has a low spin state with t_(2g)^(6) e_(g)^(0) configuration at room temperature.This implies that the high OER catalytic activity of LaCoO_(3) should not be rationalized by the occupancy of eg=1 descriptor.Substituting Sr^(2+) for La^(3+) in LaCoO_(3) induces Co4+oxidation states and effectively dopes hole states into the top of valence band.A semiconductor-to-metal transition is observed for x>0.2,due to the holeinduced electronic DOS at the EF and increased hybridization between Co 3 d and O 2 p.Such an electronic modulation enhances the surface adsorption of the*OH intermediate and reduces the energy barrier for interfacial charge transfer,thus improving the OER catalytic activity in La_(1-x)Sr_(x)CoO_(3).In addition,we found that the La_(1-x)Sr_(x)CoO_(3) surface undergoes amorphization after certain period of OER measurement,leading to a partial deactivation of the electrocatalyst.High Sr doping levels accelerated the amorphization process.

The effect of temperature on ionic liquid modified Fe-N-C catalysts for alkaline oxygen reduction reaction

Modifying solid catalysts with an ionic liquid layer is an effective approach for boosting the performance of both Pt-based and non-precious metal catalysts toward the oxygen reduction reaction. While most studies operated at room temperature it remains unclear whether the IL-associated boosting effect can be maintained at elevated temperature, which is of high relevance for practical applications in low temperature fuel cells. Herein, Fe-N-C catalysts were modified by introducing small amounts of hydrophobic ionic liquid, resulting in boosted electrocatalytic activity towards the alkaline oxygen reduction reaction at room temperature. It is demonstrated that the boosting effect can be maintained and even strengthened when increasing the electrolyte temperature up to 70℃. These findings show for the first time that the incorporation of ionic liquid is a suited method to obtain advanced noble metal-free electrocatalysts that can be applied at operating temperature condition.

Dissipation-induced instabilities and symmetry

The paradox of destabilization of a conservative or non-conservative system by small dissipation,or Ziegler’s paradox（1952）,has stimulated a growing interest in the sensitivity of reversible and Hamiltonian systems with respect to dissipative perturbations.Since the last decade it has been widely accepted that dissipation-induced instabilities are closely related to singularities arising on the stability boundary,associated with Whitney’s umbrella.The first explanation of Ziegler’s paradox was given（much earlier）by Oene Bottema in 1956.The aspects of the mechanics and geometry of dissipation-induced instabilities with an application to rotor dynamics are discussed.

Multigrid One-Shot Method for PDE-Constrained Optimization Problems

This paper presents a numerical method for PDE-constrained optimization problems. These problems arise in many fields of science and engineering including those dealing with real applications. The physical problem is modeled by partial differential equations (PDEs) and involve optimization of some quantity. The PDEs are in most cases nonlinear and solved using numerical methods. Since such numerical solutions are being used routinely, the recent trend has been to develop numerical methods and algorithms so that the optimization problems can be solved numerically as well using the same PDE-solver. We present here one such numerical method which is based on simultaneous pseudo-time stepping. The efficiency of the method is increased with the help of a multigrid strategy. Application example is included for an aerodynamic shape optimization problem.

Efficiency for Sustainability—Smart Energy Management in Social Housing

An average energy consumption distribution in household at the worldwide level illustrates that more than three quarters of total consumption is contributed to room heating and almost 12% to water heating for all the living necessities. Although a slow fall of domestic energy consumption has occurred in the recent 20 years (from 1990 to 2011) with a regular decrease between ?1.2% and ?1.4%/year per dwelling as a result of a decrease income corresponding to the economic crisis in 2008, whereas energy prices for households has increase since 2004, the energy cost of paying especially for space heating and domestic hot water (DHW) supplying is still going up. At the EU level, the building sector including residential, commercial and other service buildings is regarded as the key to greater energy efficiency, because according to statistics the final energy consumption for building sector has taken the largest proportion about 40% until 2020, which is apparently higher than the share in transportation sector by 32% and industry sector by 24%. In the scope of the ongoing research and investigation on energy efficiency in residential fields and its impact on environment and climate, how to investigate smart energy management methods for the promotion of sustainable consumption and green living patterns has been already paid much attention, however it has to be studied further and thoroughly, especially among energy consumer groups whose energy costs have no or just little relevance or dependence on major income source, which leads to a lack of energy saving awareness by users. Energy consumers living in social housing buildings represent this kind of energy consumer group which receive the governmental relief fund as their family income in a great measure, they have different culture, educational and age backgrounds. This paper presents firstly some research results based on authors’ practical experiences on the projects about energy efficiency in social housing buildings in European countries, which is supposed to be introduced in the aspects of subjective and objective energy saving potentials. It is proposed to be able to provide valuable and referential advices exchange our experience on a sustainable development in affordable housing.

Domain size and charge defects affecting the polarization switching of antiferroelectric domains

The switching behavior of antiferroelectric domain structures under the applied electric field is not fully understood.In this work,by using the phase field simulation,we have studied the polarization switching property of antiferroelectric domains.Our results indicate that the ferroelectric domains nucleate preferably at the boundaries of the antiferroelectric domains,and antiferroelectrics with larger initial domain sizes possess a higher coercive electric field as demonstrated by hysteresis loops.Moreover,we introduce charge defects into the sample and numerically investigate their influence.It is also shown that charge defects can induce local ferroelectric domains,which could suppress the saturation polarization and narrow the enclosed area of the hysteresis loop.Our results give insights into understanding the antiferroelectric phase transformation and optimizing the energy storage property in experiments.

A New Sustainability Controlling Approach for Urban Water Systems： Multidimensional Risk Identification and System Analysis

There are many pressures on urban water systems in today＇s highly dynamic world. These include the diverse impacts that are summarized under the term ＂Global Change＂. At the same time, high demands on water utilities to act sustainably do exist. For this purpose, the collaborative project ＂Sustainability Controlling for Urban Water Systems＂ （NaCoSi） introduces an innovative approach with which sustainability risks can be identified and controlled. The sustainability controlling is based on common process-oriented management systems. The starting point is a system of sustainability objectives, which were developed together with practice partners from the German water sector. A method for multidimensional risk identification is introduced to identify sustainability risks. Complex networks of cause-effect relationships are disaggregated into unbranched linear causal chains, which are managed as records in a risk database. The subsequent analysis of the risk database allows the examination of cross-linked risks. Severe risk factors, vulnerable processes and sustainability objectives can thereby be identified and subsequently analyzed. The sustainability controlling was successfully tested and improved by an iterative process of case studies in cooperation with practice partners. The results of the case studies demonstrate the benefit of the project＇s interdisciplinary approach and the applicability of the sustainability controlling.

A New Rectangular Finite Element Formulation Based on Higher Order Displacement Theory for Thick and Thin Composite and Sandwich Plates

A new displacement based higher order element has been formulated that is ideally suitable for shear deformable composite and sandwich plates. Suitable functions for displacements and rotations for each node have been selected so that the element shows rapid convergence, an excellent response against transverse shear loading and requires no shear correction factors. It is completely lock-free and behaves extremely well for thin to thick plates. To make the element rapidly convergent and to capture warping effects for composites, higher order displacement terms in the displacement kinematics have been considered for each node. The element has eleven degrees of freedom per node. Shear deformation has also been considered in the formulation by taking into account shear strains ( rxz and ryz) as nodal unknowns. The element is very simple to formulate and could be coded up in research software. A small Fortran code has been developed to implement the element and various examples of isotropic and composite plates have been analyzed to show the effectiveness of the element.

制动器摩擦衬块有关稳定性判据优化的前景和障碍(一)

制动器部件改进是直接消除制动器噪声倾向的一个明显消极对抗措施。这种把不稳定固有值变成复杂平面稳定部件的过程,要求采取非恒定转子系统的结构优化,但要一一精心研究Campbell图。如一个实际研究表明,对制动器摩擦衬块结构优化的前景和障碍关系到稳定固有值的指定和提供明确的公式,使其许可人们确定选择的耦合系统具有理想的稳定的和非稳定的模式。

Influence of Anthropogenic Activities of Groundwater from Hand Dug Wells within the Precarious Settlements of Southern Abidjan,Cote d’Ivoire:Case of the Slums of Anoumabo(Marcory)and Adjouffou(Port-Bouet)

This study aims to examine the quality and quantity of the groundwater resources from hand-dug wells, within two of these slums—Anoumabo (Marcory) and Adjouffou (Port-Bouet), both located in the southern part of the city. Twenty-eight representative groundwater samples were collected from different domestic wells within the study area. In addition, water samples were collected from the adjoining surface water bodies—the ébrié lagoon and the Atlantic Ocean. The water samples were also tested for microbial indicators of fecal contamination using the conventional membrane filtration method. The groundwater samples are alkaline to acidic with pH ranging between 4.4 and 8.1. They are slightly mineralized with electrical conductivity, EC values ranging between 388 μS/cm and 1494 μS/cm. The dominant hydrochemical facies are Na-Cl, Na-SO4, Ca-Cl and Ca-SO4. Although, majority of the water samples have anions and cations concentrations conforming to the World Health Organization, alerting levels of nitrate contamination was recorded in the area. About 67 percent of the tested samples have nitrate values greater than the recommended WHO limit for drinking water (NO3 > 50 mg/ι). Exceeding high nitrate concentrations in drinking water have been medically proven to be detrimental to infant health. Microbial analyses reveal bacterial contamination at varying degrees in all of the water wells. The presence of these microbial organisms in the samples is also indicative of the presence of some other disease causing pathogens, responsible for sicknesses like cholera, diarrhea, typhoid, etc. The water wells located within Anoumabo have relatively higher levels of groundwater contaminants in comparison to those located within Adjouffou. This is obviously due to the poor well designs and prevalent unhygienic and poor sanitary habits of its inhabitants. These waters though completely unsuitable for drinking and domestic purposes, can be used for irrigation purposes with very little or no sodium problems.