Aboard current ships, such as the DDG 51, engineering control and damage control activities are manpower intensive. It is anticipated that, for future combatants, the workload demand arising from operation of systems ...
详细信息
Aboard current ships, such as the DDG 51, engineering control and damage control activities are manpower intensive. It is anticipated that, for future combatants, the workload demand arising from operation of systems under conditions of normal steaming and during casualty response will need to be markedly reduced via automated monitoring, autonomous control, and other technology initiatives. Current DDG 51 class ships can be considered as a manpower baseline and under Condition III typical engineering control involves seven to eight watchstanders at manned stations in the Central Control Station, the engine rooms and other machinery spaces. In contrast to this manning level, initiatives such as DD 21 and the integrated engineering plant (IEP) envision a partnership between the operator and the automation system, with more and more of the operator's functions being shifted to the automation system as manning levels decrease. This paper describes some human systems integration studies of workload demand reduction and, consequently, manning reduction that can be achieved due to application of several advancedtechnology concepts. advanced system concept studies in relation to workload demand are described and reviewed including. Piecemeal applications of diverse automation and remote control technology concepts to selected high driver tasks in current DDG 51 activities. Development of the reduced ship's crew by virtual presence system that will provide automated monitoring and display to operators of machinery health, compartment conditions, and personnel health. The IEP envisions the machinery control system as a provider of resources that are used by various consumers around the ship. Resource needs and consumer priorities are at all times dependent upon the ship's current mission and the availability of equipment pawnbrokers.
Taking underwater robots project as an example, this paper discusses the innovation of the teaching mode of engineering drawing courses under the guidance of a project. The traditional engineering drawing course often...
详细信息
In this work,a morphology transition mode is revealed in ultra-high molecular weight polyethylene(UHMWPE)when stretching at 120℃:moving from the slightly deformed region to the necked region,the morphology transfers ...
详细信息
In this work,a morphology transition mode is revealed in ultra-high molecular weight polyethylene(UHMWPE)when stretching at 120℃:moving from the slightly deformed region to the necked region,the morphology transfers from small spherulites to a mixture of transcrystalline and enlarged spherulites,and finally to pure transcrystalline;meanwhile,the lamellae making up the transcrystalline or spherulite were fragmented into smaller ones;spatial scan by wide-angle X-ray scattering(WAXS)and small angle X-ray scattering(SAXS)revealed that the crystallinity is increased from 25.3%to 30.1%and the crystal orientation was enhanced greatly,but the lamellae orientation was quite *** rise of enlarged spherulites or a mixture of transcrystalline and spherulites can also be found in UHMWPE stretched at 140 and 148℃,whereas absent in UHMWPE stretched at 30℃.In situ WAXS/SAXS measurements suggest that during stretching at 30℃,the crystallinity is reduced drastically,and a few voids are formed as the size increases from 50 nm to 210 nm;during stretching at 120℃,the crystallinity is reduced only slightly,and the kinking of lamellae occurs at large Hencky strain;during stretching at 140 and 148℃,an increase in crystallinity with stretching strain can be found,and the lamellae are also *** the microstructure and morphology transition into consideration,a mesoscale morphology transition mode is proposed,in the stretching-induced crystallization the fragmented lamellae can be rearranged into new supra-structures such as spherulite or transcrystalline during hot stretching.
During flight, dragonfly wings can be thought of as an extreme light-weight airfoil. Many of the flight properties of tiny dragonfly wings are also shared by micro aerial vehicles (MAVs), which are nowadays finding wi...
详细信息
Grid-following voltage source converter(GFLVSC)and grid-forming voltage source converter(GFM-VSC)have different dynamic characteristics for active power-frequency and reactive power-voltage supports of the power *** p...
详细信息
Grid-following voltage source converter(GFLVSC)and grid-forming voltage source converter(GFM-VSC)have different dynamic characteristics for active power-frequency and reactive power-voltage supports of the power *** paper aims to clarify and recognize the difference between gridfollowing(GFL)and grid-forming(GFM)frequency-voltage support more intuitively and ***,the phasor model considering circuit constraints is established based on the port circuit equations of the *** is revealed that the voltage and active power linearly correspond to the horizontal and vertical axes in the phasor space referenced to the grid voltage ***,based on topological homology,GFL and GFM controls are transformed and mapped into different *** topological similarity of the characteristic curves for GFL and GFM controls is the essential cause of their *** on the above model,it is indicated that GFL-VSC and GFM-VSC possess uniformity with regard to active power response,type of coupling,and phasor *** differ in synchronization,power coupling mechanisms,dynamics,and active power-voltage operation domain in the quasi-steady *** studies are undertaken on GFL-VSC and GFM-VSC integrated into a four-machine two-area *** results verify that the dynamic uniformity and difference of GFL-VSC and GFM-VSC are intuitively and comprehensively revealed.
Precise transverse emittance assessment in electron beams is crucial for advancing high-brightness beam *** opposed to intricate methodologies that use specialized devices,quadrupole focusing strength scanning(Q-scann...
详细信息
Precise transverse emittance assessment in electron beams is crucial for advancing high-brightness beam *** opposed to intricate methodologies that use specialized devices,quadrupole focusing strength scanning(Q-scanning)techniques offer notable advantages for various injectors owing to their inherent convenience and ***,their stringent approximation conditions lead to inevitable errors in practical operation,thereby limiting their widespread *** study addressed these challenges by revisiting the analytical derivation procedure and investigating the effects of the underlying approximation *** corrections were explored through a combination of data processing analysis and numerical ***,based on theoretical derivations,virtual measurements using beam dynamics calculations were employed to evaluate the correction *** experimental validations were performed at the Huazhong University of Science and technology injector to verify the effectiveness of the proposed compensation *** the virtual and experimental results confirm the feasibility and reliability of the enhanced Q-scanning-based diagnosis for transverse emittance in typical beam injectors operating under common *** the integration of these corrections and compensations,enhanced Q-scanning-based techniques emerge as promising alternatives to traditional emittance diagnosis methods.
The traditional power system dominated by synchronous generators is gradually evolving into a power system with high penetration of inverter-based resources(IBRs).In this paper,the new characteristics that arise from ...
详细信息
The traditional power system dominated by synchronous generators is gradually evolving into a power system with high penetration of inverter-based resources(IBRs).In this paper,the new characteristics that arise from the high penetration of IBRs in power systems are *** light of these characteristics,current simulation technologies are inadequate and new requirements for the simulation platforms have been *** response,this paper introduces the rapid system prototype(RSP)-based physical simu-lation platforms,which include the digital simulator,the rapid prototype controller,and the rapid object-controlled *** addresses the time-consuming and labour-intensive shortcomings of traditional simulation techniques and meets the rapid evolu-tion needs of the power system with high penetration of *** with existing simulation platforms,RSP is a more suitable platform for the physical simulation of power systems with high penetration of *** the modular multilevel converter-based high-voltage direct current as a case study,a novel physical simulation platform for power systems based on RSP is *** results demonstrate that the RSP concept and technology can establish an enterprise-level simulation environment and engineering practice ***,it can provide realistic and flexible simu-lations of various characteristics of power systems with high penetration of IBRs.
Cr2AlC,a representative MAX phase,gains increasing attention for the excellent oxidation tolerance and corrosion resistance used in harsh high temperature and strong radiation ***,the lack of the phase formation mecha...
详细信息
Cr2AlC,a representative MAX phase,gains increasing attention for the excellent oxidation tolerance and corrosion resistance used in harsh high temperature and strong radiation ***,the lack of the phase formation mechanism has become the key bottleneck to the practical applications for Cr2AlC synthesis with high purity at low *** this work,we fabricated the amorphous Cr-Al-C coating by a hybrid magnetron sputtering/cathodic arc deposition technique,in which the in-situ heating transmission electron microscopy(TEM)was conducted in a temperature range of 25-650 ℃ to address the real-time phase transformation for Cr2AlC *** results demonstrated that increas-ing the temperature from 25 to 370 ℃ led to the structural transformation from amorphous Cr-Al-C to the crystalline Cr2Al ***,the high-purity Cr2AlC MAX phase was distinctly formed at 500 ℃,accompanied by the diminished amorphous *** the further increase of temperature to 650 ℃,the decomposition of Cr2AlC to Cr7C3 impurities was *** phase evolution was also evidenced by the Ab-initio molecular dynamics calculations,where the bond energy of Cr-Cr,Cr-Al,and Cr-C played the key role in the formed crystalline stability during the heating *** observa-tions not only provide fundamental insight into the phase formation mechanism for high-purity Cr2AlC coatings but also offer a promising strategy to manipulate the advanced MAX phase materials with high tolerance to high-temperature oxidation and heavy ion radiations.
Dear Editor,H∞This letter develops a new framework for the robust stability and performance conditions as well as the relevant controller synthesis with respect to uncertain robot *** often exist model uncertainties ...
详细信息
Dear Editor,H∞This letter develops a new framework for the robust stability and performance conditions as well as the relevant controller synthesis with respect to uncertain robot *** often exist model uncertainties between the nominal model and the real robot manipulator and disturbances. Hence, dealing with their effects plays a crucial role in leading to high tracking performances, as discussed in [1]–[5].
To obtain high-entropy carbide(HEC)joints with excellent high-temperature performance,a(HfZrTiTaNb)C HEC joint featuring a direct diffusion-bonded interface with a Nb-based interlayer was successfully fabricated at re...
详细信息
To obtain high-entropy carbide(HEC)joints with excellent high-temperature performance,a(HfZrTiTaNb)C HEC joint featuring a direct diffusion-bonded interface with a Nb-based interlayer was successfully fabricated at relatively low temperatures of 1150–1250℃for 60 min under 10 *** from a modified Ni/Nb/Ni composite interlayer with a Nb content of>64 at%,an alloyed Nb_(2)Ni layer was constructed in situ by accelerating the directional diffusion of Ni atoms from the high-entropy interface into the remaining pure Nb through the Ni‒Nb eutectic ***,the excess liquid phase was squeezed out of the bonding region,ensuring the absence of Ni-based *** the intrinsic interfacial stability and sluggish diffusion effect,the HEC with its original lattice structure,was capable of developing diffusion bonding with the Nb_(2)Ni layer instead of interacting with the liquid *** high reliability of the HEC/Nb_(2)Ni bonded interface was confirmed by the coherence of(11¯3)_(HEC)//(141)_(Nb_(2))Ni and a calculated lattice misfit of *** HEC joint had a high room-temperature strength of 174 MPa because of the homogenous Nb_(2)Ni layer,which exhibited nanohardness(15.2±1.5 GPa)and an elastic modulus of 219.9±17.5 ***,the strength of the HEC joint did not decrease at 1000℃,increasing by~49%over that of HEC/Ni/HEC diffusion-bonded joints,which have stringent surface flatness *** suggested that the HEC/Nb_(2)Ni interface had excellent resistance to high-temperature softening,even though it was invariably the initial failure *** work is informative for designing bonding structures and preparing HEC components.
暂无评论