Dielectric engineering enable to lateral anti-ambipolar MoTe2 heterojunction

Atomically two-dimensional (2D) materials have generated widespread interest for novel electronics and optoelectronics. Specially, owing to atomically thin 2D structure, the electronic bandgap of 2D semiconductors can be engineered by manipulating the surrounding dielectric environment. In this work, we develop an effective and controllable approach to manipulate dielectric properties of h-BN through gallium ions (Ga+) implantation for the first time. And the maximum surface potential difference between the intrinsic h-BN (h-BN) and the Ga+ implanted h-BN (Ga+-h-BN) is up to 1.3 V, which is characterized by Kelvin Probe Force Microscopy (KPFM). More importantly, the MoTe2 transistor stacked on Ga+-h-BN exhibits p-type dominated transfer characteristic, while the MoTe2 transistor stacked on the intrinsic h-BN behaves as n-type, which enable to construct MoTe2 heterojunction through dielectric engineering of h-BN. The dielectric engineering also provides good spatial selectivity and allows to build MoTe2 heterojunction based on a single MoTe2 flake. The developed MoTe2 heterojunction shows stable anti-ambipolar behaviour. Furthermore, we preliminarily implemented a ternary inverter based on anti-ambipolar MoTe2 heterojunction. Ga+ implantation assisted dielectric engineering provides an effective and generic approach to modulate electric bandgap for a wide variety of 2D materials. And the implementation of ternary inverter based on anti-ambipolar transistor could lead to new energy-efficient logical circuit and system designs in semiconductors.

Designing the Insulation System for Motors in Electrified Aircraft: Optimization, Partial Discharge Issues and Use of Advanced Materials

Designing the insulation system for motors to be used in electrical aircraft requires efforts for maximizing specific power, but, in parallel, particular attention to achieve high reliability. As a major harm for organic insulation systems is partial discharges, design must be able to infer their likelihood during any operation stage and handle their potential inception. This paper proposes a new approach to carry out optimized or conservative insulation system designs which can provide the specified life at the chosen failure probability as well as look at the option of possibly reducing the risk of partial discharges to zero, at any altitude. Examples of designing turn, phase to ground and phase-to-phase insulation systems are reported, with cases where the design can be optimized and other cases where the optimized design does not pass IEC testing standard. Therefore, the limits for design feasibility as a function of the required level of safety and reliability are discussed, showing that the presence of partial discharges cannot be always avoided even through conservative design criteria. Therefore, the use of advanced, corona-resistant materials must be considered, in order to reach a higher, sometimes redundant, level of reliability.

Power optimization of binary division based on FPGA

In modern very large scale integrated (VLSI) digital systems, power consumption has become a critical concern of VLSI designers. As size shrinks and density increases in chips, it will be a challenge to design high performance and low-power digital systems. Therefore, VLSI designers are trying to reduce power dissipation in these systems by using power optimization techniques. Different mathematical operations can be found in the architectures of most digital systems. The focus of this paper is division. In comparison to other basic computational operations, division requires more iterations, takes a long time, covers a large area, and consumes more power from the digital system. As a result, the system's design requires high speed and a low-power divider in order to improve its overall performance. This paper focuses on dynamic power dissipation. In order to determine which design consumes the lowest dynamic power, different system designs of digit-recurrence division algorithms, such as restoring division and non-restoring division are suggested. An innovative power-optimization technique, the very hardware descriptions language (VHDL) technique, is utilized to the suggested system designs. The VHDL technique achieved the higher optimization in dynamic power, at 93.66% for non-restoring division with internal-loop iteration, than traditional approaches.

Algorithm design for wind prediction in Berakit Bay, Bintan Island using Long Short-Term Memory (LSTM) method

Wind speed is a crucial parameter alongside coastal areas, especially Indonesia. Above average wind speed can cause harmful effects on human activities. This study uses wind speed data from Berakit Bay, Bintan Island is a potential location for coastal community settlement, fisheries, and tourist activities. The wind parameter then predicted using the Long Short-Term Memory or LSTM algorithm. This algorithm is able to study long-term dependencies by converting simple nervous system designs into specialized blocks containing cells. It is suitable to be applied to long-term wind predictions where the wind speed at this time is very influential with the wind speed in the future. In preparing the LSTM, the data preprocessing and the architecture used will determine the prediction results. In this study, four different architectures were made in order to determine the most optimal architecture. The results show that the LSTM architecture is able to obtain a relatively good RMSE value of 1.87 and an accuracy of 39.40% with the use of two LSTM layers, 256 units in the first layer and 128 in the second layer. The LSTM algorithm in predicting wind can also be applied to other areas in Indonesia.

Human-Centered Recommender Systems: Origins, Advances, Challenges, and Opportunities

From the earliest days of the field, Recommender Systems research and practice has struggled to balance and integrate approaches that focus on recommendation as a machine learning or missing-value problem with ones that focus on machine learning as a discovery tool and perhaps persuasion platform. In this article, we review 25 years of recommender systems research from a human-centered perspective, looking at the interface and algorithm studies that advanced our understanding of how system designs can be tailored to users objectives and needs. At the same time, we show how external factors, including commercialization and technology developments, have shaped research on human-centered recommender systems. We show how several unifying frameworks have helped developers and researchers alike incorporate thinking about user experience and human decision-making into their designs. We then review the challenges, and the opportunities, in today’s recommenders, looking at how deep learning and optimization techniques can integrate with both interface designs and human performance statistics to improve recommender effectiveness and usefulness

Study of Gob-Side Entry Retaining Technology with Roof Cutting under Upper Roadway Condition

Gob-side entry retaining technology with roof cutting (GERRC) has been widely used in flat and near-flat coal seam conditions, but its application under inclined coal seam is still very deficient. In order to further improve the application system of GERRC and overcome the application difficulties under special geological conditions, this paper takes the 43073 working face of Yixin coal mine as an example to research the GERRC with upper roadway under gently inclined thick coal seam. Firstly, the difficulties in the upper entry retaining with inclined coal seam are analyzed and the corresponding key technologies and system designs are put forward. Subsequently, the roof cutting and upper entry retaining are designed in detail according to geological conditions of test working face, and the roof cutting and pressure releasing effect is analyzed by numerical simulation to expound the stress distribution and pressure releasing mechanism of surrounding rock. Finally, the upper entry retaining field test is carried out to verify the feasibility and applicability of the technology and related designs. Through field monitoring, it is found that the weighting step increases significantly, the weighting strength decreases effectively on the roof cutting side, and the pressure relief effect is obvious. Meanwhile, the maximum roof to floor convergence is 361 mm and the maximum shrinkage of both sides is 280 mm, so the retained entry can meet the reuse requirement of adjacent working face.

Explorative Study of Aquaponics Systems in Indonesia

Aquaponics is the combined cultivation of fish in aquaculture systems and plants in hydroponic systems. This study aimed to explore and evaluate new aquaponics system designs in Jakarta, Indonesia, in terms of water and nutrient efficiency, and/or profitability. In total, one brackish water system with barramundi and tomato (BW) and three freshwater systems with Nile tilapia, rice, and duckweed (FW + DW), Nile tilapia and rice (FW − DW), and Nile tilapia and tomato (FW-tomato) were investigated using dynamic mathematical models. The results showed an increase of N, P, and water use efficiency by 10%, 18%, and 31%, respectively, in FW-tomato compare to FW − DW. Meanwhile, FW + DW only slightly increased the efficiency but worsened the already negative net present value (NPV) of FW − DW due to the high land prices. The BW system had similar water and nutrient efficiency to FW-tomato, but lower NPV. Profit of the BW and FW-tomato becomes comparable if the hydroponic area in the BW system can be expanded by 35%, or the selling price of tomato or fish in the BW can be increased by 20%. Given the expected growth of both the production of tomatoes and aquaculture in Indonesia, there is potential for further introduction of aquaponics systems in Indonesia.

New Laboratory and Pilot Techniques Applied at Mintek in Aid of Furnace Containment System Designs

The Pyrometallurgy Division at Mintek is known internationally for the development of applications of direct current (DC) arc furnace technology in smelting applications, more specifically in the smelting of primary resources, i.e., chromite, ilmenite, titanomagnetite, nickel laterite and ores containing precious group metals, and secondary resources, i.e., furnace slag or dust. From a furnace containment perspective, either an insulating or a conductive design philosophy can be applied, irrespective of the raw material being processed. In the initial stages of a project, desktop studies are typically conducted which include the selection of a furnace containment design philosophy, specific to the application. To lower the risk associated with incorrect selection of a design philosophy and/or furnace containment system components, it is prudent to conduct tests on laboratory and pilot scale and to transfer the knowledge gained to industrial applications. The paper presents examples of the laboratory and pilot techniques utilized.