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Article

Z.B. Xing, Xingchao Han, Hanbing Ke, Q.G. Zhang, Zhiping Zhang, Huijin Xu and Fuqiang Wang

A combination of highly conductive porous media and nanofluids is an efficient way for improving thermal performance of relevant applications. For precisely predicting the…

Abstract

Purpose

A combination of highly conductive porous media and nanofluids is an efficient way for improving thermal performance of relevant applications. For precisely predicting the flow and thermal transport of nanofluids in porous media, the purpose of this paper is to explore the inter-phase coupling numerical methods.

Design/methodology/approach

Based on the lattice Boltzmann (LB) method, this study combines the convective flow, non-equilibrium thermal transport and phase interactions of nanofluids in porous matrix and proposes a new multi-phase LB model. The micro-scale momentum and heat interactions are especially analyzed for nanoparticles, base fluid and solid matrix. A set of three-phase LB equations for the flow/thermal coupling of base fluid, nanoparticles and solid matrix is established.

Findings

Distributions of nanoparticles, velocities for nanoparticles and the base fluid, temperatures for three phases and interaction forces are analyzed in detail. Influences of parameters on the nanofluid convection in the porous matrix are examined. Thermal resistance of nanofluid convective transport in porous structures are comprehensively discussed with the models of multi-phases. Results show that the Rayleigh number and the Darcy number have significant influences on the convective characteristics. The result with the three-phase model is mildly larger than that with the local thermal non-equilibrium model.

Originality/value

This paper first creates the multi-phase theoretical model for the complex coupling process of nanofluids in porous structures, which is useful for researchers and technicians in fields of thermal science and computational fluid dynamics.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0961-5539

Keywords

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Article

Iman Mazinani, Mohammad Mohsen Sarafraz, Zubaidah Ismail, Ahmad Mustafa Hashim, Mohammad Reza Safaei and Somchai Wongwises

Two disastrous Tsunamis, one on the west coast of Sumatra Island, Indonesia, in 2004 and another in North East Japan in 2011, had seriously destroyed a large number of…

Abstract

Purpose

Two disastrous Tsunamis, one on the west coast of Sumatra Island, Indonesia, in 2004 and another in North East Japan in 2011, had seriously destroyed a large number of bridges. Thus, experimental tests in a wave flume and a fluid structure interaction (FSI) analysis were constructed to gain insight into tsunami bore force on coastal bridges.

Design/methodology/approach

Various wave heights and shallow water were used in the experiments and computational process. A 1:40 scaled concrete bridge model was placed in mild beach profile similar to a 24 × 1.5 × 2 m wave flume for the experimental investigation. An Arbitrary Lagrange Euler formulation for the propagation of tsunami solitary and bore waves by an FSI package of LS-DYNA on high-performance computing system was used to evaluate the experimental results.

Findings

The excellent agreement between experiments and computational simulation is shown in results. The results showed that the fully coupled FSI models could capture the tsunami wave force accurately for all ranges of wave heights and shallow depths. The effects of the overturning moment, horizontal, uplift and impact forces on a pier and deck of the bridge were evaluated in this research.

Originality/value

Photos and videos captured during the Indian Ocean tsunami in 2004 and the 2011 Japan tsunami showed solitary tsunami waves breaking offshore, along with an extremely turbulent tsunami-induced bore propagating toward shore with significantly higher velocity. Consequently, the outcomes of this current experimental and numerical study are highly relevant to the evaluation of tsunami bore forces on the coastal, over sea or river bridges. These experiments assessed tsunami wave forces on deck pier showing the complete response of the coastal bridge over water.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

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Article

Yang Chen and Fuchun Sun

The authors want to design an adaptive grasping control strategy without setting the expected contact force in advance to maintain grasping stable, so that the proposed…

Abstract

Purpose

The authors want to design an adaptive grasping control strategy without setting the expected contact force in advance to maintain grasping stable, so that the proposed control system can deal with unknown object grasping manipulation tasks.

Design/methodology/approach

The adaptive grasping control strategy is proposed based on bang-bang-like control principle and slippage detection module. The bang-bang-like control method is designed to find and set the expected contact force for the whole control system, and the slippage detection function is achieved by dynamic time warping algorithm.

Findings

The expected contact force can adaptively adjust in grasping tasks to avoid bad effects on the control system by the differences of prior test results or designers. Slippage detection can be recognized in time with variation of expected contact force manipulation environment in the control system. Based on if the slippage caused by an unexpected disturbance happens, the control system can automatically adjust the expected contact force back to the level of the previous stable state after a given time, and has the ability to identify an unnecessary increasing in the expected contact force.

Originality/value

Only contact force is used as feedback variable in control system, and the proposed strategy can save hardware components and electronic circuit components for sensing, reducing the cost and design difficulty of conducting real control system and making it easy to realize in engineering application field. The expected contact force can adaptively adjust due to unknown disturbance and slippage for various grasping manipulation tasks.

Details

Industrial Robot: the international journal of robotics research and application, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0143-991X

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Article

Ryan Rudy and Wiah Wardiningsih

This study aimed to determine the peak impact force and force attenuation capacity of weft-knitted spacer fabrics intended for padding that can be used for human body…

Abstract

Purpose

This study aimed to determine the peak impact force and force attenuation capacity of weft-knitted spacer fabrics intended for padding that can be used for human body protection against impact.

Design/methodology/approach

A total of five weft-knitted spacer fabrics were fabricated with four different diameters of nylon monofilament yarns and one doubled monofilament yarns, respectively. The impact performances of the weft-knitted spacer fabrics were tested using a drop test method with a customized test rig to simulate falling. Impact tests were conducted on single- and multilayered experimental spacer fabrics to investigate the peak impact force and force attenuation capacity.

Findings

It was found that weft-knitted spacer fabric with a coarser or larger diameter of monofilament spacer yarn generated lower impact force and higher force attenuation capacity, thus resulting in better impact performance. Greater force attenuation can be achieved by utilizing a higher number of spacer fabric layers. However, the increase in thickness must be considered with the spacer fabric end use.

Originality/value

This study employed relatively coarse nylon monofilament yarn as spacer yarns to gain knowledge on the impact performance of weft-knitted spacer fabrics compared to warp-knitted spacer fabrics which are more common. The results showed that the diameter of spacer yarn significantly influenced the impact performance of the experimental weft-knitted spacer fabrics. These results could be useful for designing and engineering textile-based impact protectors.

Details

International Journal of Clothing Science and Technology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0955-6222

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Article

Shijie Dai, Shining Li, Wenbin Ji, Zhenlin Sun and Yufeng Zhao

This study aims to realize the constant force grinding of automobile wheel hub.

Abstract

Purpose

This study aims to realize the constant force grinding of automobile wheel hub.

Design/methodology/approach

A force control strategy of backstepping + proportion integration differentiation (PID) is proposed. The grinding end effector is installed on the flange of the robot. The robot controls the position and posture of the grinding end actuator and the grinding end actuator controls the grinding force output. First, the modeling and analysis of the grinding end effector are carried out, and then the backstepping + PID method is adopted to control the grinding end effector to track the expected grinding force. Finally, the feasibility of the proposed method is verified by simulation and experiment.

Findings

The simulation and experimental results show that the backstepping + PID strategy can track the expected force quickly, and improve the dynamic response performance of the system and the quality of grinding and polishing of automobile wheel hub.

Research limitations/implications

The mathematical model is based on the pneumatic system and ideal gas, and ignores the influence of friction in the working process of the cylinder, so the mathematical model proposed in this study has certain limitations. A new control strategy is proposed, which is not only used to control the grinding force of automobile wheels, but also promotes the development of industrial control.

Social implications

The automatic constant force grinding of automobile wheel hub is realized, and the manpower is liberated.

Originality/value

First, the modeling and analysis of the grinding end effector are carried out, and then the backstepping + PID method is adopted to control the grinding end effector to track the expected grinding force. The nonlinear model of the system is controlled by backstepping method, and in the process, the linear system composed of errors is obtained, and then the linear system is controlled by PID to realize the combination of backstepping and PID control.

Details

Industrial Robot: the international journal of robotics research and application, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0143-991X

Keywords

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Article

Liang Zhong, Feifei Li, Yuxin Peng, Qiang Yang, Mingming Zhang and Jian Wang

This paper aims to propose a type of T-shaped two-axis force sensor for measuring the forces in x- and z-axes. The developed sensor has a simple structure and can be…

Abstract

Purpose

This paper aims to propose a type of T-shaped two-axis force sensor for measuring the forces in x- and z-axes. The developed sensor has a simple structure and can be effectively assembled into compact devices.

Design/methodology/approach

A T-shaped plate, with both ends fixed on a base, is used as the substrate of the sensor. Eight strain gauges are placed in the root of the plate or near the sensor head, which can construct two full Wheatstone bridges on the upper and lower surfaces of the plate. When the x- or z-axes forces are applied to the sensor head, different deformation can be generated to the strain gauges. Therefore, the two Wheatstone bridges can be constructed with a different configuration for measuring the forces in x- or z-axes, respectively.

Findings

A prototype was designed and constructed and experiments were carried out to test the basic performance of the sensor. It has been verified that the developed sensor could measure the x- and z-axes forces independently with a high resolution of 2.5 and 5 mN, respectively.

Originality/value

Only one thin plate was used in the design, the forces in x- and z-axes could be measured independently and simultaneously, which made the sensor with a simple structure and compact size. Experiments were also verified that there was no crosstalk error occurred in one axis when the force was applied to the other axis.

Details

Sensor Review, vol. 39 no. 6
Type: Research Article
ISSN: 0260-2288

Keywords

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Book part

Irina Farquhar and Alan Sorkin

This study proposes targeted modernization of the Department of Defense (DoD's) Joint Forces Ammunition Logistics information system by implementing the optimized…

Abstract

This study proposes targeted modernization of the Department of Defense (DoD's) Joint Forces Ammunition Logistics information system by implementing the optimized innovative information technology open architecture design and integrating Radio Frequency Identification Device data technologies and real-time optimization and control mechanisms as the critical technology components of the solution. The innovative information technology, which pursues the focused logistics, will be deployed in 36 months at the estimated cost of $568 million in constant dollars. We estimate that the Systems, Applications, Products (SAP)-based enterprise integration solution that the Army currently pursues will cost another $1.5 billion through the year 2014; however, it is unlikely to deliver the intended technical capabilities.

Details

The Value of Innovation: Impact on Health, Life Quality, Safety, and Regulatory Research
Type: Book
ISBN: 978-1-84950-551-2

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Book part

Paola Palacios

Purpose – The forced rural–urban migration in Colombia is a phenomenon that could be seen as the collateral damage of an armed conflict that takes place mainly in rural…

Abstract

Purpose – The forced rural–urban migration in Colombia is a phenomenon that could be seen as the collateral damage of an armed conflict that takes place mainly in rural areas. Nevertheless, there is a significant percentage of cases in which the main reason to flee is a direct threat by an armed actor. This chapter proposes a possible reason why an illegal armed group displaces population from rural to urban areas.

Design/methodology/approach – A two-stage game theoretical model is considered, in which the central government struggles over the control of a region with the insurgents. In the first stage, rebels have the choice of forcing a proportion of peasants out of the rural areas or not. In the second stage, both players choose the level of military expenditure.

Findings – It is found that, under certain circumstances, the displaced population could be used by the insurgents as a means to deter the central government from fighting. This model predicts that the larger the value rebels attached to the contested region, the higher the proportion of forced migrants. It is also consistent with the idea that if the central government can commit to warfare, then forced migration will be useless for rebels.

Originality/value – This chapter explores a new rationale for forced displacement which consists in lowering government's incentives to fight for a region, by reducing the remaining population which in turn reduces income for the government.

Details

Ethnic Conflict, Civil War and Cost of Conflict
Type: Book
ISBN: 978-1-78052-131-2

Keywords

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Book part

Rosalie Arcala Hall

Since the democratic transition in 1986, the Philippines has made considerable progress in re-establishing the legal/constitutional basis of civilian supremacy…

Abstract

Since the democratic transition in 1986, the Philippines has made considerable progress in re-establishing the legal/constitutional basis of civilian supremacy. Legislative control over the military's budget and appointment as well as the use of paramilitary units were re-instituted. Congress also assigned civilian court jurisdiction over human rights cases involving state security forces. An independent human rights commission was given power to investigate allegations of abuses. Constitutional limits were written into the President's ability to mobilize and deploy the military during emergency situations. Notwithstanding, the present structure of the Philippine security forces remains problematic. Of the three services, the army is primarily focused on counterinsurgency (COIN) operations, with the police and paramilitary providing support. The army relies on large formations for its COIN operations and less on Special Forces, which owing to historical interventionist and coup-plotting proclivities, has been numerically emasculated.

Using a case study method, the chapter probes how local civilian authorities in Leon, Iloilo (a town in central Philippines) are able to monitor, supervise or control security sector activities within their area of jurisdiction. A considerable gap exists between each force's understanding of its functions and what they actually do in relation to other state security forces. The army performs mostly non-combat tasks in line with COIN as well as non-traditional tasks. The police are involved mostly in law enforcement and provide augmentation force to army-led COIN operations, but greatly handicapped in detection and investigation matters. The paramilitary is utilized primarily for COIN as territorial defense forces but not for other emergency tasks as envisioned in the law. A tighter relationship exists on the ground between the army unit and the paramilitary, whereas a gap is evident between the army and the police regarding the geographic scope of response to rebel threat. The local government played no significant role in the peace initiative brokered in the 1990s nor has the town peace and order council been the framework of choice in seeking more constructive engagements between the civilian authorities and security forces.

Details

Advances in Military Sociology: Essays in Honor of Charles C. Moskos
Type: Book
ISBN: 978-1-84855-893-9

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Book part

Charuka Ekanayake

This Chapter is written in an era in which the United Nations (UN) routinely deploys Missions to environments that satisfy the armed conflict threshold. Such Missions

Abstract

This Chapter is written in an era in which the United Nations (UN) routinely deploys Missions to environments that satisfy the armed conflict threshold. Such Missions often require personnel to employ significant levels of force, whether to safeguard mission and humanitarian personnel, to protect civilians, to neutralise violent armed groups or, in pure self-defence. But use as well as non-use of force can readily frustrate the very objectives these troops are deployed to uphold, in turn creating gaps between the Promises they make and the Outcomes they actually secure. On the other hand, current Missions such as MINUSMA in Mali have proven to be amongst the deadliest for UN troops in the entire history of UN Peacekeeping. The thin line between use and non-use of force must therefore be trodden with utmost care. This Chapter tries to find answers to this dilemma from a moral perspective and considers how the peculiar nature of the morality of resort to force by the UN influences that of its use of force. It assesses why the latter should be calibrated or adjusted to comply with the former, and how this can consequently channel UN troop conduct towards the objectives pursued through deployment. It is only where these realities are understood and addressed, the Chapter submits, that the aforementioned Gaps between Promises and Outcomes can be redressed and closed.

Details

War, Peace and Organizational Ethics
Type: Book
ISBN: 978-1-83982-777-8

Keywords

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