Gate-tunable black phosphorus spin valve with nanosecond spin lifetimes

Two-dimensional materials offer new opportunities for both fundamental science and technological applications, by exploiting the electron spin. While graphene is very promising for spin communication due to its extraordinary electron mobility, the lack of a band gap restricts its prospects for semiconducting spin devices such as spin diodes and bipolar spin transistors. The recent emergence of 2D semiconductors could help overcome this basic challenge. In this letter we report the first important step towards making 2D semiconductor spin devices. We have fabricated a spin valve based on ultra-thin (5 nm) semiconducting black phosphorus (bP), and established fundamental spin properties of this spin channel material which supports all electrical spin injection, transport, precession and detection up to room temperature (RT). Inserting a few layers of boron nitride between the ferromagnetic electrodes and bP alleviates the notorious conductivity mismatch problem and allows efficient electrical spin injection into an n-type bP. In the non-local spin valve geometry we measure Hanle spin precession and observe spin relaxation times as high as 4 ns, with spin relaxation lengths exceeding 6 um. Our experimental results are in a very good agreement with first-principles calculations and demonstrate that Elliott-Yafet spin relaxation mechanism is dominant. We also demonstrate that spin transport in ultra-thin bP depends strongly on the charge carrier concentration, and can be manipulated by the electric field effect

Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall

For the past several years, the JET scientific programme (Pamela et al 2007 Fusion Eng. Des.82 590) has been engaged in a multi-campaign effort, including experiments in D, H and T, leading up to 2020 and the first experiments with 50%/50% D–T mixtures since 1997 and the first ever D–T plasmas with the ITER mix of plasma-facing component materials. For this purpose, a concerted physics and technology programme was launched with a view to prepare the D–T campaign (DTE2). This paper addresses the key elements developed by the JET programme directly contributing to the D–T preparation. This intense preparation includes the review of the physics basis for the D–T operational scenarios, including the fusion power predictions through first principle and integrated modelling, and the impact of isotopes in the operation and physics of D–T plasmas (thermal and particle transport, high confinement mode (H-mode) access, Be and W erosion, fuel recovery, etc). This effort also requires improving several aspects of plasma operation for DTE2, such as real time control schemes, heat load control, disruption avoidance and a mitigation system (including the installation of a new shattered pellet injector), novel ion cyclotron resonance heating schemes (such as the three-ions scheme), new diagnostics (neutron camera and spectrometer, active Alfvèn eigenmode antennas, neutral gauges, radiation hard imaging systems...) and the calibration of the JET neutron diagnostics at 14 MeV for accurate fusion power measurement. The active preparation of JET for the 2020 D–T campaign provides an incomparable source of information and a basis for the future D–T operation of ITER, and it is also foreseen that a large number of key physics issues will be addressed in support of burning plasmas.This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 and 2019–2020 under grant agreement No. 633053Postprint (published version

Water Integration for Squamscott Exeter (WISE): Preliminary Integrated Plan, Final Technical Report

This document introduces the goals, background and primary elements of an Integrated Plan for the Lower Exeter and Squamscott River in the Great Bay estuary in southern New Hampshire. This Plan will support management of point (wastewater treatment plant) and nonpoint sources in the communities of Exeter, Stratham and Newfields. The Plan also identifies and quantifies the advantages of the use of green infrastructure as a critical tool for nitrogen management and describes how collaboration between those communities could form the basis for an integrated plan. The Plan will help communities meet new wastewater and proposed stormwater permit requirements. Critical next steps are need before this Plan will fulfill the 2018 Nitrogen Control Plan requirements for Exeter and proposed draft MS4 requirements for both Stratham and Exeter. These next steps include conducting a financial capability assessment, development of an implementation schedule and development of a detailed implementation plan. The collaborative process used to develop this Plan was designed to provide decision makers at the local, state and federal levels with the knowledge they need to trust the Plan’s findings and recommendations, and to enable discussions between stakeholders to continue the collaborative process. This Plan includes the following information to guide local response to new federal permit requirements for treating and discharging stormwater and wastewater: Sources of annual pollutant load quantified by type and community; Assessment and evaluation of different treatment control strategies for each type of pollutant load; Assessment and evaluation of nutrient control strategies designed to reduce specific types of pollutants; Evaluation of a range of point source controls at the wastewater treatment facility based on regulatory requirements; Costs associated with a range of potential control strategies to achieve reduction of nitrogen and other pollutants of concern; and A preliminary implementation schedule with milestones for target load reductions using specific practices for specific land uses at points in time; Recommendations on how to implement a tracking and accounting program to document implementation; Design tools such as BMP performance curves for crediting the use of structural practices to support nitrogen accounting requirements; and Next Steps for how to complete this Plan

Recent developments in hole cleaning technology in deviated well bores for geothermal and petroleum

This paper is looking on recent developments in hole cleaning technologies and how recent advancements can be used to aid efficient hole cleaning in deviated wells. Successful hole cleaning relies upon integrating optimum drilling fluid properties with the best drilling practices. The ability of the drilling fluid to transport the drilling cuttings to the are determined by several parameters (cutting density, mud weight, hole-size, hole-angle, rheology of fluid, cutting size, rate of penetration, drill pipe eccentricity, drill pipe rotation speed, phase of fluid, cutting transport ratio and cutting bed properties). Efficient hole cleaning of deviated wells is important and difficult to perform efficiently, deviated wells normally uses drilling fluid with lower viscosity and gel building properties than in vertical section. Deviated wells are an important tool to either boost the return from existing fields or gaining access to new and formerly inaccessible formations. The increasing need for oil and gas have kept increasing with ever increasing energy output in the world, despite the world trying to swap to more renewable resources. Petroleum products such as coal, gas and oil still stand for over 80% of the energy production in the world. Increasing energy demands from the world exceeds the development within renewable technologies and gaining access to new formation and extracting most of the oil and gas in current formation will be paramount in giving people access to energy required to keep the world running. Percentage of world’s energy coming from renewable resources has increased and will hopefully keep increasing, but total energy demand especially from developing countries with increasing population and higher standard of living requires higher amount of energy than the countries are currently consuming with renewable being too expensive, inefficient, or lacking the required infrastructure for implementation. The paper is a compilation of recent developments and would hopefully give the reader insight in the processes most important efficient hole cleaning for deviated wells. The topic of efficient hole cleaning is complex, and a lot of different parameters will be introduced to understand the role of new developments. Basic understanding of these parameters and their interplay with each other is required to understand to keep the innovation with respect to efficient hole cleaning and automating more of the process involved in hole cleaning while drilling in deviated wells. The paper also uses the information from collected studies to write to a data code based on recent developments to aid in controlling the right rate of penetration (ROP) during drilling. No independent research was those in this paper and is based on the work of research and literature of others

PBM and DEM simulations of large-scale closed-circuit continuous ball mill of cement clinker

Cement milling is known to be inefficient and energy-intensive. Thus, even small improvements in cement milling\u27s performance could significantly reduce operation costs. This dissertation aims to develop a simulation tool for dry milling and generate a fundamental process understanding, which enables process optimization. To this end, a true unsteady-state simulator (TUSSIM) for continuous dry milling is developed and applied to model various processes: (a) open circuit continuous mills, (b) closed-circuit continuous mills, and (c) vertical roller mills. TUSSIM is based on the solution of the cell-based population balance model (PBM) for continuous milling, which consists of a set of differential algebraic equations (DAEs). Moreover, air classifier parameters and ball size distribution for the closed-circuit operation are tailored to maximize production capacity while achieving desirable cement product qualities. Discrete element method (DEM) and PBM are coupled to simulate lab-scale batch milling of cement clinker to gain fundamental understanding of the roles of ball size and material (steel vs. alumina). First, dynamic simulations are performed to investigate the impact of ball mill operation parameters on the full-scale open-circuit ball milling of cement clinker without an external air classifier. Parameters for the simulation are taken from the literature. Simulation results suggest that a single-compartment mill produces the desired cement size, but it requires pre-milled fresh feed. Depending on the ball sizes used, a two compartment mill produces cement sizes similar to those produced by a three-compartment mill. A uniform mass of balls achieves an 8% higher specific surface area (SSA) compared to a uniform number of balls. The classifying liners have negligibly finer cement products compared to a uniform mass distribution. TUSSIM is also incorporated with a variable Tromp curve model for classification to simulate full-scale closed-circuit ball milling with an air classifier. The simulation results suggest that a faster rotor speed or lower air flow rate leads to a finer cement product and increases the dust load of the classifier feed. Integrating air classifiers into open-circuit ball milling increases the production rate by 15% or cement SSA by 13%. Operation failure due to overloading of the entire circuit is detected when dust load is too high. Process optimization with a global optimizer?DAE solver is performed to identify either the air classifier\u27s parameters or the ball size distributions that yield desirable cement quality while maximizing production rate. Optimization results show that the production rate can be increased by 7% compared to the baseline process. Unlike open circuits, a two-compartment mill produces a finer cement product than a three-compartment mill. Optimal ball mixtures are identified in a two-compartment mill, suggesting a 14% increase in production rate at a desirable cement quality. A global optimizer-based back-calculation method, based on PBM, is used to determine the breakage kinetics parameters of cement clinker in a lab-scale ball mill loaded with steel or alumina balls of three single ball sizes and their mixtures. The motion of the balls in the mill is simulated via the DEM. The results show that steel balls achieve faster breakage of clinker than alumina balls, which is explained by the higher total?mean energy dissipation rates of the steel balls. The particle size distribution (PSD) becomes finer as smaller balls are used. The ball mixture is the most effective overall. Significant energy can be saved if steel balls are replaced with alumina balls, but the slower breakage with the alumina balls needs to be accounted for. Finally, steady-state cement PSD obtained from a full-scale vertical roller mill is fitted with TUSSIM. The fitted results show good agreement compared to the experimental PSD. Overall, this dissertation has provided a novel process simulator, TUSSIM, and many fundamental insights into the continuous milling of cement clinker and its optimization

Implementation of membrane processes for improvement of the detection of food contaminants

The EM3E Master is an Education Programme supported by the European Commission, the European Membrane Society (EMS), the European Membrane House (EMH), and a large international network of industrial companies, research centres and universities (http://www.em3e.eu)Food borne pathogen is a topmost important concern of present era due to deteriorating the food quality, contributing significant loss in the health aspect, global nutritional demand and economy. A rapid, fast and effective analytic system of pathogen identification and enumeration is the vital most important tool towards minimization of both the grasp and effect of pathogen contamination whereas the performance and accuracy of almost all of presently developed respective sensory tools are localized on the molecular recognition and catalytic processes of the sensor that work for the detection and enumeration. The presence of other biological molecules except the targets imparts significant unwanted ligand interaction which deteriorates its true binding efficiency of the specific ligand with exact orientation and frequency; and thus requires the pre-treatments of the sample to minimize such interference. Keeping this on mind, in this work, a membrane process has developed for the purification of the targets (the cells) by removal of the other unwanted interfering species from the Listeria innocua loaded food (milk) sample followed by concentration of the sample. Both the type of bacteria and host food were selected due to high demand. The selective concentration of the cells and volume reduction of target cells from the milk sample was accomplished by diafiltration (DF) and tangential flow filtration (TFF) with microfiltration (MF) membrane. The effect of cell loading on the cell purification and concentration by filtration performance of milk was analyzed. Comparative analysis between TFF and DF was done on this aspect and a combined protocol has developed. The analysis of operational parameters (e.g. TMP, CFV, permeate flux behaviour, system configuration, etc.) on the chemical composition of permeate and retentate was studied. A mass-balance based model was developed and used to predict the trend of concentrations of the species along the progress of DF process. The organic load removal from the system was found to be positively correlated with the TMP and CFV involved while the cell recovery was found efficient in an optimum TMP range. The system was found efficient with fastness, effective cell purifying and concentrating capability, high recovery of membrane and easiness to operate with more than 99.7% of viable cell isolation for further use in bio-sensing tool

Design and implementation of a domestic disinfection robot based on 2D lidar

In the battle against the Covid-19, the demand for disinfection robots in China and other countries has increased rapidly. Manual disinfection is time-consuming, laborious, and has safety hazards. For large public areas, the deployment of human resources and the effectiveness of disinfection face significant challenges. Using robots for disinfection therefore becomes an ideal choice. At present, most disinfection robots on the market use ultraviolet or disinfectant to disinfect, or both. They are mostly put into service in hospitals, airports, hotels, shopping malls, office buildings, or other places with daily high foot traffic. These robots are often built-in with automatic navigation and intelligent recognition, ensuring day-to-day operations. However, they usually are expensive and need regular maintenance. The sweeping robots and window-cleaning robots have been put into massive use, but the domestic disinfection robots have not gained much attention. The health and safety of a family are also critical in epidemic prevention. This thesis proposes a low-cost, 2D lidar-based domestic disinfection robot and implements it. The robot possesses dry fog disinfection, ultraviolet disinfection, and air cleaning. The thesis is mainly engaged in the following work: The design and implementation of the control board of the robot chassis are elaborated in this thesis. The control board uses STM32F103ZET6 as the MCU. Infrared sensors are used in the robot to prevent from falling over and walk along the wall. The Ultrasonic sensor is installed in the front of the chassis to detect and avoid the path's obstacles. Photoelectric switches are used to record the information when the potential collisions happen in the early phase of mapping. The disinfection robot adopts a centrifugal fan and HEPA filter for air purification. The ceramic atomizer is used to break up the disinfectant's molecular structure to produce the dry fog. The UV germicidal lamp is installed at the bottom of the chassis to disinfect the ground. The robot uses an air pollution sensor to estimate the air quality. Motors are used to drive the chassis to move. The lidar transmits its data to the navigation board directly through the wires and the edge-board contact on the control board. The control board also manages the atmosphere LEDs, horn, press-buttons, battery, LDC, and temperature-humidity sensor. It exchanges data with and executes the command from the navigation board and manages all kinds of peripheral devices. Thus, it is the administrative unit of the disinfection robot. Moreover, the robot is designed in a way that reduces costs while ensuring quality. The control board’s embedded software is realized and analyzed in the thesis. The communication protocol that links the control board and the navigation board is implemented in software. Standard commands, specific commands, error handling, and the data packet format are detailed and processed in software. The software effectively drives and manages the peripheral devices. SLAMWARE CORE is used as the navigation board to complete the system design. System tests like disinfecting, mapping, navigating, and anti-falling were performed to polish and adjust the structure and functionalities of the robot. Raspberry Pi is also used with the control board to explore 2D Simultaneous Localization and Mapping (SLAM) algorithms, such as Hector, Karto, and Cartographer, in Robot Operating System (ROS) for the robot’s further development. The thesis is written from the perspective of engineering practice and proposes a feasible design for a domestic disinfection robot. Hardware, embedded software, and system tests are covered in the thesis