检索结果-南通市图书馆

Systems approach to underground safety

在线全文

学校读者我要写书评

暂无评论

Underground Space 2020年第3期5卷 258-266页

作者： marco Bettelini Amberg Engineering Ltd. Switzerland

The safety of underground traffic infrastructures can be considered from several viewpoints as a fairly mature *** minimum requirements for road tunnel safety were developed for all European countries in ***,safety is codified in a detailed(at times even too detailed)manner,such as for road tunnels in several *** design can at times be extremely rigid and difficult for adapting to specific conditions,which in some cases may need to be more demanding than a"standard"*** types of underground infrastructure,particularly,rail tunnels and underground industrial facilities,share a number of common safety-related issues with road tunnels,but are generally much less *** example,there is no common regulation for the ventilation of rail tunnels in *** metro systems have different safety standards,in spite of having similar *** present study illustrates selected aspects of a holistic approach required for achieving a high and sustainable safety level in underground *** aspects and differences between the various types of"conventional"and"emerging"underground infrastructure are outlined and the consequences are discussed,such as the different types of threats,widely differing probabilities of occurrence,and widely differing number of persons *** facilities require different safety systems;however,they can rely on common thinking and *** is essential for all stakeholders,ranging from operators and safety officers to fire services and administrative authorities,to grasp commonalities and differences to adapt requirements,regulations,and approaches to their specific needs.

关键词： Safety Underground space Tunnel

On the use of Max-SAT and PDDL in RBAC maintenance

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Cybersecurity 2018年第1期1卷 592-616页

作者： marco Benedetti marco Mori Bank of Italy ICT DepartmentCentro Donato MenichellaRomaItaly

Role-Based Access Control(RBAC)policies are at the core of Cybersecurity as they ease the enforcement of basic security principles,e.g.,Least Privilege and Separation of *** ICT systems and business processes evolve,RBAC policies have to be updated to prevent unauthorised access to resources by capturing errors and misalignments between the current policy and ***,such update process is a human-intensive activity and it is expected to meet specific *** paper proposes a semi-automatic RBAC maintenance process to fix and refine an RBAC state when“exceptions”and“violations”are *** are permissions some users realise they miss that are instrumental to their job and should be granted as soon as possible,while violations are permissions that have to be revoked since they are no longer required by their current *** propose a formalisation for the maintenance process which fixes single and multiple exceptions and violations by balancing two conflicting objectives,i.e.,(i)optimising the current RBAC state,and(ii)reducing the transition *** approach is based on a Max-SAT formalisation of the constraint-based optimisation problem,and on PDDL planning to define the transition strategy with minimum *** implementation relies on incomplete Max-SAT solvers and satisficing PDDL planners which provide approximations of optimal *** along with a comparative evaluation show good performance on real-world benchmarks.

关键词： RBAC maintenance Max-SAT PDDL planner RBAC evolution

Classical model for diffusion and thermalization of heavy quarks in a hot medium: memory and out-of-equilibrium effects

维普期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2019年第9期43卷 90-100页

作者： marco Ruggieri marco Frasca Santosh Kumar Das School of Nuclear Science and Technology Lanzhou University222 South Tianshui RoadLanzhou 730000China Via Erasmo Gattamelata Rome 00176Italy School of Physical Science Indian Institute of Technology GoaPonda-403401GoaIndia

We consider a simple model for the diffusion of heavy quarks in a hot bath,modeling the latter by an ensemble of oscillators distributed according to either a thermal distribution or to an out-of-equilibrium distribution with a saturation *** this model it is easy to introduce memory effects by changing the distribution of oscillators:we model them by introducing a Gaussian distribution,dN/dω,which can be deformed continuously from aδ?function,giving a Markov dissipation,to a broad kernel with *** the equation of motion of the heavy quark in the bath,we remark how dissipation comes out naturally as an effect of the back-reaction of the oscillators on the ***,the exact solution of this equation allows to define the thermalization time as the time necessary to remove any memory of the initial *** find that the broadening of the dissipative kernel,while keeping the coupling fixed,lowers the thermalization *** also derive the fluctuation-dissipation theorem for the bath,and use it to estimate the kinematic regime in which momentum diffusion of the heavy quark dominates over *** find that diffusion is more important as long as K0/E is small,where K0 and E denote the initial energy of the heavy quark and the average energy of the bath,respectively.

关键词： relativistic heavy ion collisions heavy quarks Brownian motion memory effect quark-gluon plasma

Topology Search of 3-DOF Translational Parallel Manipulators with Three Identical Limbs for Leg Mechanisms

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2015年第4期28卷 666-675页

作者： WANG Mingfeng CECCARELLI marco LARM:Laboratory of Robotics and Mechatronics University of Cassino and South Latium

Three-degree of freedom（3-DOF） translational parallel manipulators（TPMs） have been widely studied both in industry and academia in the past decades. However, most architectures of 3-DOF TPMs are created mainly on designers＇ intuition, empirical knowledge, or associative reasoning and the topology synthesis researches of 3-DOF TPMs are still limited. In order to find out the atlas of designs for 3-DOF TPMs, a topology search is presented for enumeration of 3-DOF TPMs whose limbs can be modeled as 5-DOF serial chains. The proposed topology search of 3-DOF TPMs is aimed to overcome the sensitivities of the design solution of a 3-DOF TPM for a LARM leg mechanism in a biped robot. The topology search, which is based on the concept of generation and specialization in graph theory, is reported as a step-by-step procedure with desired specifications, principle and rules of generalization, design requirements and constraints, and algorithm of number synthesis. In order to obtain new feasible designs for a chosen example and to limit the search domain under general considerations, one topological generalized kinematic chain is chosen to be specialized. An atlas of new feasible designs is obtained and analyzed for a specific solution as leg mechanisms. The proposed methodology provides a topology search for 3-DOF TPMs for leg mechanisms, but it can be also expanded for other applications and tasks.

关键词： topology search 3-DOF translational parallel manipulators(TPMs) creative design leg mechanisms

Design issues for human-machine platform interface in cable-based parallel manipulators for physiotherapy applications

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第4期11卷 231-239页

作者： marco CECCARELLI Lotfi ROMDHANE Laboratory of Robotics and Mechatronics DIMSATUniversity of Cassino-CassinoItaly Département de Mécanique Avancée Ecole Nationale d'Ingénieurs de SousseTunisia

We outline problems and potential solutions for feasible human-machine interfaces using cable-based parallel manipulators for physiotherapy *** an engineering perspective,we discuss the design constraints related to acceptance by patients and physiotherapist *** date,most designs have focused on mobile platforms that are designed to be operated as an end-effector connected to human limbs for direct patient *** specific examples are illustrated from the authors' experience with prototypes available at Laboratory of Robotics and Mechatronics (LARM),Italy.

关键词： Robot design Robot applications Cable-based parallel manipulators Human-machine mechanical interfaces

Experimental Characterization of Operation of a Waist-Trunk System with Parallel Manipulators

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2011年第5期24卷 713-722页

作者： CECCARELLI marco CARBONE Giuseppe Laboratory of Robotics and Mechatronics (LARM) University of Cassino

An extensive research activity has been focused on the upper and lower limbs of humanoid robots. However, due to mechanical design difficulties and complex control of multi-body system, the torso of humanoid robot is somehow a neglected or simplified design part. In this paper, operation performance of a new waist-trunk system as torso for humanoid robots is presented through results of lab experimental tests. The proposed waist-trunk system is composed of two 3 DOFs （degrees of freedom） parallel manipulators, which are connected in a serial chain architecture. A prototype is built by using two prototypes of CaPaMan （Cassino Parallel Manipulator）, which are convenient stiff architectures with easy-operation characteristics. Experimental tests are carried out with the aims to imitate lateral-bending and transverse-rotation movements of human torso. Operation performances like displacements, accelerations, and actuation torque are measured for a performance evaluation and design characterization of the used manipulator solution imitating human torso. Experimental test results are illustrated and discussed to show the practical operation feasibility of the proposed architecture and the operation characteristics of the built prototype.

关键词： humanoid robots waist-trunk system parallel manipulators experimental robotics

Effect of Heat Loss on Laminar Flamelet Species Concentration

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2016年第5期25卷 418-423页

作者： marco Boccanera Diego Lentini Dipartimento di Ingegneria Meccanica e Aerospaziale Sapienza Università di Roma

The effects of heat loss on the structure of laminar flamelets,which are the constitutive elements of turbulent flames under the most common operating conditions,are investigated for typical aeronautical gas-turbine operating conditions at *** magnitude of heat loss is quantified via the "enthalpy defect" measured with respect to an adiabatic flame.A procedure to generate laminar flamelets with an assigned enthalpy defect at the boundaries is devised and applied to nonpremixed propane/air flames,as propane reproduces the essential features of higher hydrocarbon *** is found,contrary to commonly held beliefs,that the enthalpy defect has a significant effect on the concentration not only of minor species,but also of main reaction *** effects are found in general to be more pronounced for fuel-rich *** impact is anticipated on the formation rate of nitric *** effects of scalar dissipation rate are also discussed.

关键词： Turbulent Combustion Heat Transfer Laminar Flamelets Hydrocarbon Combustion Aeroengines Gas Turbines

Estimation of the behavior factor of existing RC-MRF buildings

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2018年第1期17卷 191-204页

作者： marco Vona Monica Mastroberti School of Engineering University of Basilicata

In recent years, several research groups have studied a new generation of analysis methods for seismic response assessment of existing buildings. Nevertheless, many important developments are still needed in order to define more reliable and effective assessment procedures. Moreover, regarding existing buildings, it should be highlighted that due to the low knowledge level, the linear elastic analysis is the only analysis method allowed. The same codes（such as NTC2008, EC8） consider the linear dynamic analysis with behavior factor as the reference method for the evaluation of seismic demand. This type of analysis is based on a linear-elastic structural model subject to a design spectrum, obtained by reducing the elastic spectrum through a behavior factor. The behavior factor（reduction factor or q factor in some codes） is used to reduce the elastic spectrum ordinate or the forces obtained from a linear analysis in order to take into account the non-linear structural capacities. The behavior factors should be defined based on several parameters that influence the seismic nonlinear capacity, such as mechanical materials characteristics, structural system, irregularity and design procedures. In practical applications, there is still an evident lack of detailed rules and accurate behavior factor values adequate for existing buildings. In this work, some investigations of the seismic capacity of the main existing RC-MRF building types have been carried out. In order to make a correct evaluation of the seismic force demand, actual behavior factor values coherent with force based seismic safety assessment procedure have been proposed and compared with the values reported in the Italian seismic code, NTC08.

关键词： seismic behavior existing buildings seismic safety assessment behavior factor

Investigation of mechanical behaviour of a quasi-brittle material using Karagozian and Case concrete (KCC) model

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2019年第6期11卷 1119-1137页

作者： Aria Mardalizad marco Caruso Andrea Manes marco Giglio Politecnico di Milano Department of Mechanical EngineeringMilanItaly Politecnico di Milano Material Testing LaboratoryMilanItaly

The mechanical behaviour of a quasi-brittle material,*** Serena sandstone,was investigated both numerically and experimentally in order to build a reliable numerical modelling system applicable to more complex *** Karagozian and Case concrete(KCC)model was exploited as the material constitutive law and a new method to utilise this model for efficient and accurate simulation of quasibrittle materials is *** capability of this model is evaluated by comparing the results of the numerical simulations with the corresponding experimental results,and the method itself is critically assessed.

关键词： Finite element method (FEM) Triaxial compression test Brazilian disc test Quasi-brittle behaviour Karagozian and Case concrete (KCC) model