Non-intrusive load monitoring (NILM) provides homeowners with detailed feedback on their electricity usage, but an open area is appliance labeling and generalizable appliance models that can be ...trained in one home and deployed in another. We therefore propose a semi-supervised learning appliance annotation scheme for home appliance signatures (SARAA). SARAA utilizes time series of appliance turn on and turn off events to tune generic appliance classifiers to appliances in the target home using a mixture of labeled and unlabeled data. Achieving this goal requires the development of a stopping criterion for semi-supervised learning, and we propose and evaluate a stopping heuristic for one-nearest neighbor semi-supervised learning of appliance signature time series. Starting with only a single labeled instance in the target home, SARAA produces classifiers with median F1 scores only 14.8% lower than benchmark classifiers trained on the fully labeled ground truth data in the target home, outperforming classifiers trained only on data from other homes, which have a median F1 score that is 51.23% poorer than the benchmark. The results of this paper will help develop NILM systems, which can automatically learn appliance signatures without user input and facilitate wider adoption of NILM technologies.
Smart grid is an intelligent power generation, distribution, and control system. ZigBee, as a wireless mesh networking scheme low in cost, power, data rate, and complexity, is ideal for smart grid ...applications, e.g., real-time system monitoring, load control, and building automation. Unfortunately, almost all ZigBee channels overlap with wireless local area network (WLAN) channels, resulting in severe performance degradation due to interference. In this paper, we aim to develop practical ZigBee deployment guideline under the interference of WLAN. We identify the "Safe Distance" and "Safe Offset Frequency" using a comprehensive approach including theoretical analysis, software simulation, and empirical measurement. In addition, we propose a frequency agility-based interference avoidance algorithm. The proposed algorithm can detect interference and adaptively switch nodes to "safe" channel to dynamically avoid WLAN interference with small latency and small energy consumption. Our proposed scheme is implemented with a Meshnetics ZigBit Development Kit and its performance is empirically evaluated in terms of the packet error rate (PER) using a ZigBee and Wi-Fi coexistence test bed. It is shown that the empirical results agree with our analytical results. The measurements demonstrate that our design guideline can efficiently mitigate the effect of WiFi interference and enhance the performance of ZigBee networks.
In this paper, we study the problem of secure key management for smart grid. Since existing key management schemes are not suitable for deployment in smart grid, in this paper, we propose a novel key ...management scheme which combines symmetric key technique and elliptic curve public key technique. The symmetric key scheme is based on the Needham-Schroeder authentication protocol. We show that the known threats including the man-in-the-middle attack and the replay attack can be effectively eliminated under the proposed scheme. The advantages of the new key management scheme include strong security, scalability, fault-tolerance, accessibility, and efficiency.
•Firm’s end-of-season product promotion through online channel is presented.•Equilibrium online channel format between agency selling and reselling is obtained.•Effects of promotional pricing timing ...and uncertain demand are investigated.•Promotional pricing timing affects firm’s decisions only in reselling format.•Agency selling format is no longer profitable under certain conditions.
Firms typically introduce online promotional channels based on the cooperative format of agency selling or reselling to promote end-of-season products. The selection of the agency selling or reselling format is greatly affected by a firm’s pricing timing between traditional and online promotional channels, particularly in an uncertain market. Within this context, we examine how the pricing timings in an online promotional channel relative to a traditional channel impact a firm’s selection between agency selling and reselling formats in an uncertain market. We find that the promotional pricing timings have no effect on the firm’s price decisions under the agency selling format, whereas they might lead to downward prices under the reselling format—even lower than those under the agency selling format. We show that considering promotional pricing timing in an uncertain market fundamentally changes the general intuition that the firm prefers the agency selling to reselling format due to the double-marginalization effect. Specifically, the reselling format might be more profitable for the firm when it sets traditional-channel promotional price prior to introducing the online promotional channel in an optimistic market (i.e., a market more likely to have high demand) or adopts the opposite promotional pricing timing of channels in a pessimistic market (i.e., a market more likely to have low demand). Our findings complement the emerging online retail literature by underscoring the interacting forces of promotional pricing timing and uncertain demand on a firm’s reselling versus agency selling format choice in promoting end-of-season product online.
Among different printing techniques, direct ink writing is commonly used to fabricate 3D battery and supercapacitor electrodes. The major advantages of using the direct ink writing include ...effectively building 3D structure for energy storage devices and providing higher power density and higher energy density than traditional techniques due to the increased surface area of electrode. Nevertheless, direct ink writing has high standards for the printing inks, which requires high viscosity, high yield stress under shear and compression, and well-controlled viscoelasticity. Recently, a number of 3D-printed energy storage devices have been reported, and it is very important to understand the printing process and the ink preparation process for further material design and technology development. We discussed current progress of direct ink writing technologies by using various electrode materials including carbon nanotube-based material, graphene-based material, LTO (Li4Ti5O12), LFP (LiFePO4), LiMn1-xFexPO4, and Zn-based metallic oxide. Based on achieve electrochemical performance, these 3D-printed devices deliver performance comparable to the energy storage device fabricated using traditional methods still leaving large room for further improvement. Finally, perspectives are provided on the potential future direction of 3D printing for all solid-state electrochemical energy storage devices.
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•The 2D and 3D structures of energy storage devices are reviewed.•Energy storage devices are printed using different materials by 3D direct writing.•The 3D devices deliver a better performance than traditional fabrication methods.
Electric vehicles (EVs) with large battery charging demands may cause detrimental impact on distribution grid stability without EV charging coordination. This paper proposes an on-line adaptive EV ...charing scheduling (OACS) framework to optimize EV charging schedules and reduce flow limit, voltage magnitude limit, 3-phase voltage imbalance limit, and transformer capacity violations. EV user convenience is considered and EV charging cost is optimized. DC power flow based optimizations is proposed for EV charging scheduling approximation and parallel ac power flow verification is used to verify the scheduling results. Incremental feasibility improvement procedure is further proposed to correct the scheduling discrepancy between dc linear model and the ac model. Experiments are performed on a modified IEEE 34 14.7 kV distribution system with different EV penetration levels to demonstrate performance comparisons between different scheduling schemes. The result shows that our proposed OACS framework optimizes the EV charging coordination problem efficiently.
Purpose - The purpose of this paper is to present a mask-image-projection-based stereolithography (MIP-SL) process that can combine two base materials with various concentrations and structures to ...produce a solid object with desired material characteristics. Stereolithography is an additive manufacturing process in which liquid photopolymer resin is cross-linked and converted to solid. The fabrication of digital material requires frequent resin changes during the building process. The process presented in this paper attempts to address the related challenges in achieving such fabrication capability.Design methodology approach - A two-channel system design is presented for the multi-material MIP-SL process. In such a design, a coated thick film and linear motions in two axes are used to reduce the separation force of a cured layer. The material cleaning approach to thoroughly remove resin residue on built surfaces is presented for the developed process. Based on a developed testbed, experimental studies were conducted to verify the effectiveness of the presented process on digital material fabrication.Findings - The proposed two-channel system can reduce the separation force of a cured layer by an order of magnitude in the bottom-up projection system. The developed two-stage cleaning approach can effectively remove resin residue on built surfaces. Several multi-material designs have been fabricated to highlight the capability of the developed MIP-SL process.Research limitations implications - A proof-of-concept testbed has been developed. Its building speed and accuracy can be further improved. The tests were limited to the same type of liquid resins. In addition, the removal of trapped air is a challenge in the presented process.Originality value - This paper presents a novel and a pioneering approach towards digital material fabrication based on the stereolithography process. This research contributes to the additive manufacturing development by significantly expanding the selection of base materials in fabricating solid objects with desired material characteristics.
A major challenge for effective application of CRISPR systems is to accurately predict the single guide RNA (sgRNA) on-target knockout efficacy and off-target profile, which would facilitate the ...optimized design of sgRNAs with high sensitivity and specificity. Here we present DeepCRISPR, a comprehensive computational platform to unify sgRNA on-target and off-target site prediction into one framework with deep learning, surpassing available state-of-the-art in silico tools. In addition, DeepCRISPR fully automates the identification of sequence and epigenetic features that may affect sgRNA knockout efficacy in a data-driven manner. DeepCRISPR is available at http://www.deepcrispr.net/ .
Itraconazole is an FDA‐approved antifungal agent, which has been reported to possess promising anticancer activities in recent years. This study investigates the antiproliferative effects of ...itraconazole on pancreatic cancer cells and the molecular mechanism of its apoptosis‐inducing effects. In this study, our results showed that itraconazole inhibited the growth of pancreatic cancer cells in vitro, and it also significantly inhibited the tumor growth of CFPAC‐1 xenografts in vivo. Itraconazole induced apoptosis through ROS generation and mitochondrial membrane depolarization. A Bak‐1 activation dependent apoptosis was identified in CFPAC‐1 cells. These data suggested that itraconazole exhibited antiproliferative effects in pancreatic cancer cells by inducing apoptosis through Bak‐1 activation.
Itraconazole inhibited the growth of pancreatic cancer cells in vitro, and it also significantly inhibited the tumor growth of CFPAC‐1 xenografts in vivo. Itraconazole induced apoptosis through ROS generation and mitochondrial membrane depolarization.
The use of catalysts is the key to boost electrode reactions in lithium–oxygen (Li–O2) batteries. In-depth understanding of the nanoscale catalytic effect at electrode/electrolyte interfaces is of ...great significance for guiding a design of functionally optimized catalyst. Here, using electrochemical atomic force microscopy, we present the real-time imaging of interfacial evolution on nanostructured Au electrodes in a working battery, revealing that the nanostructure of Au is directly related to the catalytic activity toward oxygen reduction reaction (ORR)/oxygen evolution reaction (OER). In situ views show that nanoporous Au with a size of ∼14 nm for ligaments and ∼5 nm for nanopores promote the nucleation and growth of discharge product Li2O2 with large size at a high discharge voltage, yet densely packed Au nanoparticles with a diameter of ∼15 nm could catalyze Li2O2 to fully decompose via the top-bottom approach at a low charge potential. In addition, the difference in the nucleation potential of Li2O2 on the electrode with hybrid nanostructures could result in an uneven distribution of discharge products, which is alleviated at a large discharge rate and the capacity of the battery is improved significantly. These observations provide deep insights into the mechanisms of Li–O2 interfacial reaction catalyzed by nanostructured catalysts and strategies for improving Li–O2 batteries.
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