Increasing the powerdensity and overload capability of the energy-supply units(ESUs)is always one of the most challenging tasks in developing anddeploying legged vehicles,especially for heavy-duty legged vehicles,in...
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Increasing the powerdensity and overload capability of the energy-supply units(ESUs)is always one of the most challenging tasks in developing anddeploying legged vehicles,especially for heavy-duty legged vehicles,in which significant power fluctuations in energy supply exist with peak power several times surpassing the average *** ESUs with high powerdensity and high overload can compactly ensure fluctuating power source supply on *** can avoid the ultra-high configuration issue,which usually exists in the conventional lithium-ion battery-based or engine-generator-based ***,it dramatically reduces weight and significantly increases the loading and endurance capabilities of the legged *** this paper,we present a hybrid energy-supply unit for a heavy-duty legged vehicle combining the discharge characteristics of lithium-ion batteries and peak energy release/absorption characteristics of supercapacitors to adapt the ESU to high overload power *** parameters of the lithium-ion battery pack and supercapacitor pack inside the ESU are optimally matched using the genetic algorithm based on the energy consumption model of the heavy-duty legged *** experiment results exhibit that the legged vehicle with a weight of 4.2 tons can walk at the speed of 5 km/h in a tripod gait under a reduction of 35.39%in weight of the ESU compared to the conventional lithium-ion battery-based solution.
Serving as the initiating explosive devices between the propellant tank and the engines,metal-basedrupture diaphragms are widely used in ramjet igniters owing to the advantages provided by their simple structure,smal...
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Serving as the initiating explosive devices between the propellant tank and the engines,metal-basedrupture diaphragms are widely used in ramjet igniters owing to the advantages provided by their simple structure,small size,and low ***,the reliability of rupture pressure directly affects the success of engine ignition androcket launch,which is mainly influenced by factors like material,structure,andresidual thickness of the surface notch of the *** those,the geometry of the notch is easy to define and control when compared to the mechanical parameters of the ruptured ***,to make the diaphragm rupture(1A30 Al)within the required pressure range(0.4 MPa±3.5%)with highly sensitive andreliability,we draw inspiration from the arthropod’s force-sensitive slit organ which encompasses curved microgrooves to design a Ω-shaped notch for the rupture *** element analysis is used to study the relationship between the burst pressure and geometric dimension of theΩ-shaped and bioinspired *** on that,metal-basedrupture diaphragms are fabricated by femtosecond laser processing technology,followed by rupture *** results demonstrate that the practical rupture pressure of the diaphragm is highly consistent with the finite element analysis results,which verifies the effectiveness of the bionic design.
Monolithic aerogels are promising candidates for use in atmospheric environmental purification due to their structural advantages,such as fine building block size together with high specific surface area,abundant pore...
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Monolithic aerogels are promising candidates for use in atmospheric environmental purification due to their structural advantages,such as fine building block size together with high specific surface area,abundant pore structure,***,monolithic aerogels possess a unique monolithic macrostructure that sets them apart from aerogel powders and nanoparticles in practical environmental clean-up *** review delves into the available synthesis strategies and atmospheric environmental applications of monolithic aerogels,covering types of monolithic aerogels including SiO_(2),graphene,metal oxides and their combinations,along with their preparation *** particular,recent developments for VOC adsorption,CO_(2)capture,catalytic oxidation of VOCs and catalytic reduction of CO_(2)are ***,challenges and future opportunities for monolithic aerogels in the atmospheric environmental purification field are *** reviewprovides valuable insights fordesigning and utilizing monolithic aerogel-based functional materials.
Heat exchangers are the core components of energy transfer and conversion and are widely used in the energy,chemical,and other *** an actual operational process,load changes lead to variations in the operating conditi...
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Heat exchangers are the core components of energy transfer and conversion and are widely used in the energy,chemical,and other *** an actual operational process,load changes lead to variations in the operating conditions of the heat *** the heat-transfer performance is crucial for the safe and efficient operation of the *** realize high-precision heat transfer prediction through simulations,instead of using traditional solid equipment,this study proposed a heat transfer prediction modeling method that combines three-dimensional high-precision and one-dimensional real-time dynamic *** method combines the high-precision advantage of three-dimensional simulation with the real-time advantage of one-dimensional *** verify the feasibility of the modeling method,a heat transfer prediction model was constructed based on the heat transfer channel structure of a CO_(2)mixture heat transfer characteristic experimental test *** steady-state anddynamic heat transfer characteristics of CO_(2)/r32 mixtures were simulated and experimentally ***,the real-time operational capability of the heat transfer prediction model was verified using a real-time *** results showed that the heat transfer prediction model modeling method proposed in this study could improve the accuracy by 1.75-4.64 times compared with the conventional one-dimensional dynamic *** established heat transfer prediction model exhibited good accuracy for both dynamic and steady-state *** average relative errors with the experimental results were in the range of 0.91%-2.83%under six sets of experimental ***,the proposed heat transfer prediction model can predict the heat transfer process in real-time under all experimental heat source conditions.
In this work,an effective catalyst of Cu/MnOOH has been successfully constructed for electrochemical nitrate reduction reaction(e NO_(3)rr)for synthesis of ammonia(NH_(3))under ambient *** substrate of MnOOH plays an ...
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In this work,an effective catalyst of Cu/MnOOH has been successfully constructed for electrochemical nitrate reduction reaction(e NO_(3)rr)for synthesis of ammonia(NH_(3))under ambient *** substrate of MnOOH plays an important role on the size and electronic structure of Cu nanoparticles,where Cu has the ultrafine size of 2.2 nm and positive shift of its valence states,which in turn causes the increased number of Cu active sites and enhanced intrinsic activity of every active *** a result,this catalyst realizes an excellent catalytic performance on eNO_(3)rr with the maximal NH_(3)Faraday efficiency(FE)(96.8%)and the highest yieldrate(55.51 mg h^(-1)cm^(-2))at a large NH_(3)partial current density of700 m A/cm^(2),which could help to promote the industrialization of NH_(3)production under ambient conditions.
Effective control of time-sensitive industrial applications depends on the real-time transmission of data from underlying *** the data freshness through age of information(AoI),in this paper,we jointly design sampling...
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Effective control of time-sensitive industrial applications depends on the real-time transmission of data from underlying *** the data freshness through age of information(AoI),in this paper,we jointly design sampling and non-slot based scheduling policies to minimize the maximum time-average age of information(MAoI)among sensors with the constraints of average energy cost and finite queue *** overcome the intractability involving high couplings of such a complex stochastic process,we first focus on the single-sensor time-average AoI optimization problem and convert the constrained Markov decision process(CMdP)into an unconstrained Markov decision process(MdP)by the Lagrangian *** the infinite-time average energy and AoI expression expended as the Bellman equation,the singlesensor time-average AoI optimization problem can be approached through the steady-state distribution ***,we propose a low-complexity sub-optimal sampling and semi-distributed scheduling scheme for the multi-sensor *** simulation results show that the proposed scheme reduces the MAoI significantly while achieving a balance between the sampling rate and service rate for multiple sensors.
The Beidou-Ⅱcivil navigation message(BdⅡ-CNAV)is transmitted in an open environment and no information integrity protection measures are ***,the BdⅡ-CNAV faces the threat of spoofing attacks,which can lead to wrong...
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The Beidou-Ⅱcivil navigation message(BdⅡ-CNAV)is transmitted in an open environment and no information integrity protection measures are ***,the BdⅡ-CNAV faces the threat of spoofing attacks,which can lead to wrong location reports and time *** order to deal with this threat,we proposed a scheme of anti-spoofing for BdⅡ-CNAV based on integrated information *** scheme generates two type authentication information,one is authentication code information(ACI),which is applied to confirm the authenticity andreliability of satellite time information,and the other is signature information,which is used to authenticate the integrity of satellite location information and other *** authentication information is designed to embed into the reserved bits in BdⅡ-CNAV without changing the frame *** order to avoid authentication failure caused by public key error orkey error,the key or public key prompt information(KPKPI)are designed to remind the receiver to update both keys in *** results indicate that the scheme can successfully detect spoofing attacks,and the authentication delay is less than 1%of the transmission delay,which meets the requirements of BdⅡ-CNAV information authentication.
L-2-Aminobutyric acid (L-2-ABA) is a nonnatural chiral alpha-amino acid which is widely used in various chiral pharmaceuticals and medical intermediates. Currently, the microbial metabolic engineering approach to enab...
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L-2-Aminobutyric acid (L-2-ABA) is a nonnatural chiral alpha-amino acid which is widely used in various chiral pharmaceuticals and medical intermediates. Currently, the microbial metabolic engineering approach to enable Escherichia coli to produce L-2-ABA autonomously exists the problem of low synthesis efficiency, limiting its large-scale application. In this study, we successfully constructed a strain of E. coli that can produce L-2-ABA efficiently via multi-pathway transformation. Firstly, the growth defect of the start strain was restored by the help of screening transcriptional regulators. To maximize the accumulation of L-2-ABA, enhancements were made to the main synthetic pathways as well as cofactor systems and energy supply. Subsequently, transport proteins associated with osmotic stress tolerance were modified to improve adaptability of the strain during fermentation. Ultimately, the titer of L-2-ABA reached 42.14 g/L through the final strain ABAT38 in a 5-liter bioreactor, with a productivity of 0.40 g/L/h and a glucose conversion of 0.39 g/g, which exceeded the highest levels reported before. The strategies proposed in this study contribute to the production of L-2-ABA. At the same time, it has reference significance for the biosynthesis of related nonnatural amino acids with phosphoenolpyruvate as the intermediate metabolite.
due to the fact that a high share of renewable energy sources(rESs)are connected to high-voltage direct current(HVdC)sending-end AC power systems,the voltage and frequency regulation capabilities of HVdC sending-end A...
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due to the fact that a high share of renewable energy sources(rESs)are connected to high-voltage direct current(HVdC)sending-end AC power systems,the voltage and frequency regulation capabilities of HVdC sending-end AC power systems have *** has resulted in potential system operating problems such as overvoltage and overfrequency,which occur simultaneously when block faults exist in the HVdC *** this study,a steady-state voltage security-constrained optimal frequency control method for weak HVdC sending-end AC power systems is *** integrated virtual inertia control of rESs is employed for system frequency *** dynamic reactive power compensation devices are utilized to control the voltage of all nodes meet voltage security ***,an optimization model that simultaneously considers the frequency and steady-state voltage security constraints for weak HVdC sending-end AC power systems is *** optimal control scheme with the minimum total cost of generation tripping and additional dynamic reactive power compensation required is obtained through the optimization *** are conducted on a modified IEEE 9-bus test system and practical Qing-Yu line commutated converter based HVdC(LCC-HVdC)sending-end AC power system to verify the effectiveness of the proposed method.
With the liberalization of the retail market,customers can sell theirdemandresponse(dr)resources to the distribution company(disco)through the dr aggregator(drA).In this paper,an intelligent drresource trading fram...
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With the liberalization of the retail market,customers can sell theirdemandresponse(dr)resources to the distribution company(disco)through the dr aggregator(drA).In this paper,an intelligent drresource trading framework between disco anddrA is proposed by exploiting the benefits of deep reinforcement learning(drL).The hierarchical decision process of the two players is modeled as a Stackelberg *** the game,disco is the leader who determines the retail price while drA is the follower who responds to *** protect their privacy,a dueling deep Q-network(dueling dQN)is then constructed to model the bi-level Stackelberg game,such that the lower-level problem doesn’t need to reveal its detailed model to the *** the learning process,the uncertainties from the drA’s baseline load and wind power are *** order to boost the robustness against the estimation error,the baseline load is discretized into symbols before being used as the input states of the dueling *** to mitigate the uncertainty of wind power,the scenario-based method is introduced when designing the *** demonstrate that the proposeddueling dQNbased method has good performance and is more robust against uncertainties.
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