Improving the operational stability of perovskite solar cells with cesium-doped graphene oxide interlayer

Perovskite solar cells(PSCs)have made great advances in terms of power conversion efficiency(PCE),yet their subpar stability continues to hinder their commercialization.The interface between the perovskite layer and the charge-carrier transporting layers plays a crucial role in undermining the stability of PSCs.In this work,we propose a strategy to stabilize high-performance PSCs with PCE over 23%by introducing a cesium-doped graphene oxide(GO-Cs)as an interlayer between the perovskite and hole-transporting material.The GO-Cs treated PSCs exhibit excellent operational stability with a projected T80(the time where the device PCE reduces to 80%of its initial value)of 2143 h of operation at the maximum powering point under one sun illumination.

Monitoring Study of Long-Term Land Subsidence during Subway Operation in High-Density Urban Areas Based on DInSAR-GPS-GIS Technology and Numerical Simulation

During subway operation,various factors will cause long-term land subsidence,such as the vibration subsidence of foundation soil caused by train vibration load,incomplete consolidation deformation of foundation soil during tunnel construction,dense buildings and structures in the vicinity of the tunnel,and changes in water level in the stratum where the tunnel is located.The monitoring of long-term land subsidence during subway operation in high-density urban areas differs from that in low-density urban construction areas.The former is the gathering point of the entire urban population.There are many complex buildings around the project,busy road traffic,high pedestrian flow,and less vegetation cover.Several existing items requiremonitoring.However,monitoring distance is long,and providing early warning is difficult.This study uses the 2.8 km operation line between Wulin Square station and Ding’an Road station of Hangzhou Subway Line 1 as an example to propose the integrated method of DInSAR-GPS-GIS technology and the key algorithm for long-term land subsidence deformation.Then,it selects multiscene image data to analyze long-termland subsidence of high-density urban areas during subway operation.Results show that long-term land subsidence caused by the operation of Wulin Square station to Ding’an Road station of Hangzhou Subway Line 1 is small,with maximumsubsidence of 30.64 mm,and minimumsubsidence of 11.45 mm,and average subsidence ranging from 19.27 to 21.33 mm.And FLAC3D software was used to verify the monitoring situation,using the geological conditions of the soil in the study area and the tunnel profile to simulate the settlement under vehicle load,and the simulation results tended to be consistent with the monitoring situation.

Voltage-dependent plasticity and image Boolean operations realized in a WOx-based memristive synapse

The development of electronic devices that possess the functionality of biological synapses is a crucial step towards neuromorphic computing.In this work,we present a WOx-based memristive device that can emulate voltage-dependent synaptic plasticity.By adjusting the amplitude of the applied voltage,we were able to reproduce short-term plasticity(STP)and the transition from STP to long-term potentiation.The stimulation with high intensity induced long-term enhancement of conductance without any decay process,thus representing a permanent memory behavior.Moreover,the image Boolean operations(including intersection,subtraction,and union)were also demonstrated in the memristive synapse array based on the above voltage-dependent plasticity.The experimental achievements of this study provide a new insight into the successful mimicry of essential characteristics of synaptic behaviors.

A Two-Stage Approach for Large-Scale Cascaded Hydropower System Operations

The paper presents a two-stage approach to cope with the long-term optimal operation of cascaded hydropower systems. This approach combines progressive optimality algorithm (POA) with quadratic programming (QP) to improve the optimization results. POA is used at the first stage to generate a local optimal result, which will be selected as the initial feasible solution of QP method employed at the second stage. Around the initial solution, a rational local search range for QP method is then determined, where the nonlinear water level function and tailrace level function can be linearized nearly with high accuracy. The simplified optimization problem is formulated as a QP model with a quadratic generation function and a linear set of constraints, and solved using the available mathematic optimization software package. Simulation is performed on the long term operation of Hongshui River hydropower system which is located in southwest China and consists of 9 built hydropower plants. Results obtained from the proposed approach show a significant increase in the total energy production compared to the results from POA.

ERROR ESTIMATE FOR INFLUENCE OF MODEL REDUCTION OF NONLINEAR DISSIPATIVE AUTONOMOUS DYNAMICAL SYSTEM ON LONG-TERM BEHAVIOURS

From viewpoint of nonlinear dynamics, the model reduction and its influence on the long-term behaviours of a class of nonlinear dissipative autonomous dynamical system with higher dimension are investigated theoretically under some assumptions. The system is analyzed in the state space with an introduction of a distance definition which can be used to describe the distance between the full system and the reduced system, and the solution of the full system is then projected onto the complete space spanned by the eigenvectors of the linear operator of the governing equations. As a result, the influence of mode series truncation on the long-term behaviours and the error estimate are derived, showing that the error is dependent on the first products of frequencies and damping ratios in the subspace spanned by the eigenvectors with higher modal damping. Furthermore, the fundamental understanding for the topological change of the solution due to the application of different model reduction is interpreted in a mathematically precise way, using the qualitative theory of nonlinear dynamics.

Research on the development mode of long-term nursing insurance ——taking Qingdao as an example

With the gradual development of society, scientific and technological progress, aging gradually aggravated, has become a hot topic of society. People to old age, self-care ability than in the past, not only suffer from disease, life has become difficult, coupled with the large number of empty nest family, the cost of care is also very high, whether it is to receive home care or professional institutions of care have great difficulties. Therefore, the community should be a large number of people with long-term care needs of the appropriate economic compensation, in this context, long-term care insurance is born. As a leading city in Shandong Province, Qingdao has introduced long-term care insurance and achieved good results. This paper analyzes the practical problems faced by Qingdao, that is, the development background of Qingdao long-term nursing insurance model, obtains the deficiency of Qingdao long-term nursing insurance, and then puts forward the corresponding countermeasures, and then ponders how to choose the long-term nursing insurance model of our country＇s future development.

Advancing immunosuppression in liver transplantation: A narrative review

Immunosuppression is essential to ensure recipient and graft survivals after liver transplantation(LT). However, our understanding and management of the immune system remain suboptimal. Current immunosuppressive therapy cannot selectively inhibit the graft-specific immune response and entails a significant risk of serious side effects, i.e., among others, de novo cancers, infections, cardiovascular events, renal failure, metabolic syndrome, and late graft fibrosis, with progressive loss of graft function. Pharmacological research, aimed to develop alternative immunosuppressive agents in LT, is behind other solidorgan transplantation subspecialties, and, therefore, the development of new compounds and strategies should get priority in LT. The research trajectories cover mechanisms to induce T-cell exhaustion, to inhibit co-stimulation, to mitigate non-antigen-specific inflammatory response, and, lastly, to minimize the development and action of donor-specific antibodies. Moreover, while cellular modulation techniques are complex, active research is underway to foster the action of T-regulatory cells, to induce tolerogenic dendritic cells, and to promote the function of B-regulatory cells. We herein discuss current lines of research in clinical immunosuppression, particularly focusing on possible applications in the LT setting.

Development of a Long-Term Operational Optimization Model for a Building Energy System Supplied by a Geothermal Field

In order to reduce energy consumption and CO_(2) emissions in the building sector, more and more renewable energy sources are integrated into energy systems. Especially geothermal fields combined with heat pumps are able to supply buildings with heat and cold at low carbon emissions. However, using geothermal fields as heat and cold source influences the ground temperature. Consequently, the ground temperature can change dramatically over a building’s lifetime, leading to less efficient operation of the energy system. Therefore, a sustainable operation is required to ensure the long-term efficiency of geothermal fields. In this paper, we develop an optimization model to derive operating strategies for an efficient long-term operation of a building energy system coupled to a geothermal field. The investigated energy system is the main building of the E.ON Energy Research Center in Aachen, Germany, which includes a heat pump, two boilers, a combined heat, and power unit, a glycol cooler, and a geothermal field with 41 probes. For each component, we develop energy-based sub-models, which are connected to form the overall system. The geothermal field is modeled by using a g-functions approach as well as a simplified resistance-capacitance approach. To achieve short computing times and realize an optimization horizon of several years, the optimization problem is formulated as mixed-integer linear programming(MILP). The developed model is optimized regarding two different objectives: the minimization of energy costs and the minimization of long-term temperature changes in the ground. Conclusions for an efficient and sustainable operation of the field, especially for the cooling supply, can be derived from the optimization results. It is shown that a state of equilibrium should be aimed to achieve an energy-efficient operation, in which the temperature of the field is close to the initial ground temperature.

Recovery of Cu(Ⅱ) from aqueous solution by induced crystallization in a long-term operation

The feasibility of copper recovery by induced crystallization in a long period（174 days） was investigated in a seeded fluidized bed reactor（FBR）. The process was divided into 3 periods according to different influent conditions, and the period Ⅲ was separated into Ⅲ-a and Ⅲb due to the adjustment of the molar ratio of CO3^2- concentration to copper concentration（[CT]/[Cu^2＋]）. The removal efficiency could exceed 95% and the average effluent copper concentration decreased to 3.0 mg/L. The mean particle size of seed grains with copper crystals coating on, raised to 0.36 mm from initial 0.18 mm. During period Ⅲ-a, the supersaturation exceeded 2.88 × 104, the removal efficiency decreased to 60%–80% and the particle size dropped to 0.30 mm, due to the generation of fines by homogeneous crystallization and seeds breaking. And the morphology of the crystals on the seed grains changed from rod-like to spherical which lead to the particle size decreasing. In period Ⅲ-b,the supersaturation was modified by adjusting the molar ratio of [CT]/[Cu^2＋] to 1.2 from 2.The efficiency was back to 95% and the mean particle size grew to 0.36 mm at the end of Ⅲb, the crystals coating on the seeds turned back to rod-like products of good stability. This study illustrated that the copper salt crystal could keep on growing on the seed grains for over 150 days, the feasibility and controllability of copper recovery by induced crystallization process in FBR were satisfactory, even under the dramatic changes in influent conditions.

A better long-term outcome in cardiac transplant recipient with a history of previous open heart operations

Objective To investigate the effect of previous open heart operations (POHO) on the outcome of heart transplantation (HTX). Methods Between November 1984 and May 1996, HTX was performed on 151 patients at Hartford Hospital. Among them, 61 patients had previous open heart operations (POHO) (group A), and 90 did not (group B). The average follow up period was 1615±1185 days for group A and 1330±1125 days for group B. The recipient age was 55±10 years for group A and 48±12 years for group B (P<0.01). There were 17 patients (26%) in group A and 14 (50%) in group B who were over 60 years of age. There was more coronary artery disease (74% versus 37%, P <0.001) as etiology, and more diabetics in group A (P<0.02). Results The time for cardiopulmonary bypass (133±20 min versus 106±18 min, P<0.01) and aortic clamp time (73±16 min versus 61±13 min, P<0.01) were longer in group A. The operative mortality (within 30 days) was 0 and 2.2%, and the cumulative deaths were 16 (26%) and 43 (48%) respectively for group A and group B (P<0.01). The causes of death were (group A vs group B): infection (31% vs 26%), rejection (13% vs 28%, P<0.05), malignancy (25% vs 16%), cardiac event (6% vs 14%) and others (25% vs 16%). In patients over 60, there were 4 deaths (24%) in group A and 7 (50%) in group B. The difference was not significant. No patients died of rejection in this subgroup. The actuarial survival rates in group A versus group B were: 1 year, 93% versus 83%; 2 years, 85% versus 74%; 3 years, 81% versus 71%; 5 years, 76% versus 58%; and 10 years, 57 % versus 24% (P<0.01). Conclusion The survival rate in patients who had POHO is much higher than that in patients who had HTX as their primary operation.

Calculating collision probability for long-term satellite encounters through the reachable domain method

ABSTRACT Satellite encounters during close operations,such as rendezvous,formation,and cluster flights,are typical long-term encounters.The collision probability in such an encounter is a primary safety concern.In this study,a parametric method is proposed to compute the long-term collision probability for close satellite operations with initial state uncertainty.Random relative state errors resulting from system uncertainty lead to possible deviated trajectories with respect to the nominal one.To describe such a random event meaningfully,each deviated trajectory sample should be mapped to a unique and time-independent element in a random variable(RV)space.In this study,the RV space was identified as the transformed state space at a fixed initial time.The physical dimensions of both satellites were characterized by a combined hard-body sphere.Transforming the combined hard-body sphere into the RV space yielded a derived ellipsoid,which evolved over time and swept out a derived collision volume.The derived collision volume was solved using the reachable domain method.Finally,the collision probability was computed by integrating a probability density function over the derived collision volume.The results of the proposed method were compared with those of a nonparametric computation-intensive Monte Carlo method.The relative difference between the two results was found to be<0.6%,verifying the accuracy of the proposed method.

Aerobic granules cultivated and operated in continuous-flow bioreactor under particle-size selective pressure

A novel method based on the selective pressure of particle size （particle-size cultivation method, PSCM） was developed for the cultivation and operation of aerobic granular sludge in a continuous-flow reactor, and compared with the conventional method based on the selective pressure of settling velocity （settling-velocity cultivation method, SVCM）. Results indicated that aerobic granules could be cultivated in continuous operation mode by this developed method within 14 days. Although in the granulation process, under particle-size selective pressure, mixed liquor suspended solids （MLSS） in the reactor fluctuated greatly and filamentous bacteria dominated the sludge system during the initial operation days, no obvious difference in profile was found between the aerobic granules cultivated by PSCM and SVCM. Moreover, aerobic granules cultivated by PSCM presented larger diameter, lower water content and higher specific rates of nitrification, denitrifieation and phosphorus removal, but lower settling velocity. Under long term operation of more than 30 days, aerobic granules in the continuous-flow reactor could remain stable and obtain good chemical oxygen demand （COD）, NH4^＋-N, total nitrogen （TN） and total phosphorus （TP） removal. The results indicate that PSCM was dependent on the cultivation and maintenance of the stability of aerobic granules in continuous-flow bioreactors.

Study on risk assessment and factors ranking of the LTE-M communication system

To assess the operational safety risk of long-term evolution for the metro(LTE-M)communication system more accurately,the guide maintenance strategy,the improved evidence theory and the multi-attribute ideal reality comparative analysis(MAIRCA)approaches are proposed.According to the features of LTE-M system,the risk evaluation system is established.The enhanced structural entropy weight method is used to obtain the weight.Furthermore,it is combined with nine-element fuzzy mathematics to transform the degree of membership,modifying the conflict and fusion rules to solve the confidence degree clashed problem of evidence theory.Then,the system risk grade assessment result is obtained.For the purpose of forming the ranking of indicator importance,the MAIRCA is introduced and the ranking is three-dimensional.The operational state of the metro line is used as the data source in various ways the obtained risk grade increased by 7.12%.It is verified that MAIRCA can be applied to the field of urban rail transit because it has based on the test and calculation.The results show that the method is effective;compared with others,the confidence degree of excellent stability and the ranking result of risk factors is reasonable.The influencing indicator with the highest importance is the'equipment failure rate".