7,997 research outputs found

    Multiparty Quantum Secret Sharing Based on Entanglement Swapping

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    A multiparty quantum secret sharing (QSS) protocol is proposed by using swapping quantum entanglement of Bell states. The secret messages are imposed on Bell states by local unitary operations. The secret messages are split into several parts and each part is distributed to a party so that no action of a subset of all the parties but their entire cooperation is able to read out the secret messages. In addition, the dense coding is used in this protocol to achieve a high efficiency. The security of the present multiparty QSS against eavesdropping has been analyzed and confirmed even in a noisy quantum channel.Comment: 5 page

    Feedback noncausal model predictive control of wave energy converters

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    In this paper, a novel feedback noncausal model predictive control (MPC) strategy for sea wave energy converters (WECs) is proposed, where the wave prediction information can be explicitly incorporated into the MPC strategy to improve the WEC control performance. The main novelties of the MPC strategy proposed in this paper include: (i) the recursive feasibility and robust constraints satisfaction are guaranteed without a significant increase in the computational burden; (ii) the information of short-term wave prediction is incorporated into the feedback noncausal MPC method to maximise the potential energy output; (iii) the sea condition for the WEC to safely operate in can be explicitly calculated. The proposed feedback noncausal MPC algorithm can also be extended to a wide class of control design problems, especially to the energy maximisation problems with constraints to be satisfied and subject to persistent but predictable disturbances. Numerical simulations are provided to show the efficacy of the proposed feedback noncausal MPC

    Effects of Ultraviolet C Irradiation on Stilbene Biosynthesis in Vitis vinifera L. cv. Cabernet Sauvignon Berry Skins and Calli

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    Vitis vinifera L. cv. Cabernet Sauvignon berries and calli were irradiated with ultraviolet C (UV-C) to investigate the effects on the biosynthesis of stilbene. The stilbene content in the berry skins was enhanced significantly after 10 min of UV-C irradiation over the 24 h time course, and the results varied depending on the development stage of the fruit. The maximum production of total stilbene in the berry skins occurred at 12 h after treatment, with a content of 848.45 ± 23.53 μg/g fresh weight (FW) at the beginning of véraison, 591.77 ± 26.90 μg/g FW at the end of véraison, and 170.71 ± 6.85 μg/g FW at the ripening stage. Different UV-C dosages, from 5 to 30 min, induced stilbene accumulation considerably in the calli over the 120 h experimental period, and 20 min was the most efficient. The maximum of total stilbene accumulation in the calli was 125.07 ± 3.01 μg/g FW at 96 h after 20 min irradiation. Total phenolics and total flavonoid content increased after UV-C irradiation in both the berry skins and calli. The relative expression of genes encoding enzymes involved in the branching point of stilbene and flavonoid biosynthesis was up-regulated by UV-C irradiation. The results show that UV-C irradiation significantly promotes stilbene and flavonoid biosynthesis in grape berry skins and calli, and the induction effects depend on fruit development stage and UV-C dosage

    Correlation between the Mean Matter Density and the Width of the Saturated Lyman Alpha Absorption

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    We report a scaling of the mean matter density with the width of the saturated Lyman alpha absorptions. This property is established using the ``pseudo-hydro'' technique (Croft et al. 1998). It provides a constraint for the inversion of the Lyman alpha forest, which encounters difficulty in the saturated region. With a Gaussian density profile and the scaling relation, a simple inversion of the simulated Lyman alpha forests shows that the one-dimensional mass power spectrum is well recovered on scales above 2 Mpc/h, or roughly k < 0.03 s/km, at z=3. The recovery underestimates the power on small scales, but improvement is possible with a more sophisticated algorithm.Comment: 7 pages, 9 figures, accepted for publication in MNRAS, replaced by the version after proo

    Intelligent comprehensive control and monitor of proton exchange membrane fuel cell for hybrid UPS system

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    This paper, to improve the performance of a Proton Exchange Membrane fuel cell (PEMFC) stack, avoid the hydrogen and oxygen/air starvation of electrochemical reaction and the performance deterioration of the stack, prevent the dehydration and drying of the membrane, keep the water content in the membrane, heighten the utilization of the gases, and track the output power of a hybrid uninterruptible power supply (UPS) system with backup PEMFC and battery power sources, conducts research in the dynamic model, the on-line parameters monitoring of PEMFC, such as the resistance in the PEMFC stack using the current interrupt method and the performance improvement of the PEMFC employing an intelligent comprehensive control strategy of the operation parameters, such as operating temperature, pressures and mass flows of hydrogen and air, the output current and voltage for the PEMFC stack, the power supply switching between PEMFC and battery. The intelligent comprehensive control and monitor method is proposed and applied to the PEMFC generating system employed for the power source of UPS. The experimental results show that the proposal method can effectively monitor and control the pressures of the inlet hydrogen and the operating temperature of the stack, automatically switch the power supply between PEMFC and battery, efficaciously prevent the destroy of the stack when the load changes sharply, the hydrogen is purged and the output current is interrupted regularly, and reasonably improve the performance of the PEMFC through the water balance and thermal management, and real-time realize the tracking for the changes of the output power and the distribution of the mass flow rates of hydrogen and air. © 2009 IEEE

    Computation Offloading in Multi-access Edge Computing using Deep Sequential Model based on Reinforcement Learning

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    This is the author accepted manuscript. The final version is available from IEEE via the DOI in this record.Multi-access Edge Computing (MEC) is an emerging paradigm which utilizes computing resources at the network edge to deploy heterogeneous applications and services. In the MEC system, mobile users and enterprises can offload computation-intensive tasks to nearby computing resources to reduce latency and save energy. When users make offloading decisions, the task dependency needs to be considered. Due to the NP-hardness of the offloading problem, the existing solutions are mainly heuristic, and therefore have difficulties in adapting to the increasingly complex and dynamic applications. To address the challenges of task dependency and adapting to dynamic scenarios, we propose a new Deep Reinforcement Learning (DRL) based offloading framework, which can efficiently learn the offloading policy uniquely represented by a specially designed Sequence-to-Sequence (S2S) neural network. The proposed DRL solution can automatically discover the common patterns behind various applications so as to infer an optimal offloading policy in different scenarios. Simulation experiments were conducted to evaluate the performance of the proposed DRL-based method with different data transmission rates and task numbers. The results show that our method outperforms two heuristic baselines and achieves nearly optimal performance.Engineering and Physical Sciences Research Council (EPSRC

    Effect of Suspension Freeze-concentration Technology on the Quality of Wine

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    One of the factors that inhibits the development of the Chinese wine industry is that the sugar content ofthe grape feedstock is insufficient. In order to produce wine with better qualities using these materials,concentrating the grape juice could be a good alternative to adding sugars. In this study, suspension freezeconcentrationtechnology was applied to concentrating grape juice with a low sugar content. The freezeconcentratedgrape juice was made into red and white wines separately. In the control group, red andwhite wines were made from chaptalized (sugar-enriched) grape juice. The physical and chemical indexes,sensory evaluation results and polyphenolic content of the wine were analysed to evaluate the practicalityof applying the freeze-concentration technology in the wine industry. The results show that, after removingice every 30 min for approximately 14 h with a -18°C coolant, grape juice with an initial sugar content of14°Brix reached 23°Brix. Both the red wines and white wines made from freeze-concentrated grape juicewere of a higher quality than the wines made from chaptalised grape juice. Moreover, the phenolic contentwas concentrated, which may provide health benefits. Thus, suspension freeze-concentration technology isa promising alternative to traditional chaptalisation technology
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