Passive gravity compensation for a mechanism is usually preferred to the active one for some reasons including cost consideration. Many technologies based on counterweight and linear springs have been widely developed, whereas the use of torsional springs is rarely discussed due to unavailability of exact mathematical manipulation to determine the required spring constants to achieve the static balance. This paper proposes the use of torsional springs for passive gravity compensation applied to a parallel kinematics mechanism. The spring constants are determined by constrained optimization approach aiming at minimizing the total potential energy of the mechanism along a prescribed trajectory within the range of motion. It is shown that the solution provides almost-statically-balanced state of the mechanism within its range of motion. This accordingly reduces the required actuation forces/torques and hence the power consumption.
In this paper, an example of applying the passive Discrete Variable Stiffness Joint (pDVSJ-II) is illustrated. A qualitative experiment in a teleoperation scenario is presented as a case study to demonstrate the effectiveness of the proposed haptic interface and to show how a human can take advantage of stiffness rendering by the proposed device in applications e.g. remote palpation. The results show that the device is capable of successfully providing information about the stiffness of two different objects through the forces acting at the remote site, thus improving the overall telepresence in such applications.
In this paper, we study a class of fractional nonlinear Volterra integro-differntial type of singularly perturbed problems with fractional order: We divide the problem into two problems. The first problem is the reduced problem when = 0: The second problem is fractional Volterra integrodifferential problem. We use the finite difference method to solve the first problem and the reproducing kernel method to solve the second problem. The results show that the proposed analytical method can achieve excellent results in predicting the solutions of such problems. Theoretical results are presented. Numerical results are presented to show the efficiency of the proposed method.
Recent advances in geometry have shown the wide application of hyperbolic geometry not only in mathematics but also real world applications. As in two dimensions, it is now clear that most threedimensional objects (configuration spaces and manifolds) are modelled on hyperbolic geometry. This viewpoint explains a great many things from large-scale cosmological phenomena, such as the shape of the universe, right down to the symmetries of groups and geometric objects and various physical theories. Kleinian groups are basically discrete groups of isometries associated with tessellations of hyperbolic space. They form the fundamental groups of hyperbolic manifolds. Over the last few decades, the theory of Kleinian groups has flourished because of its intimate connections with low-dimensional topology and geometry, especially with 3-manifold theory. In particular, we seek generalisations of known universal constraints for Fuchsian groups - discrete subgroups of isometries of hyperbolic plane. These generalisations will underpin a new understanding of the geometry and topology of hyperbolic 3-manifolds and their associated singular spaces, hyperbolic 3-orbifolds. The universal constraints for Kleinian groups we seek will in part arise from a novel description of the moduli spaces of discrete groups. This approach was successfully used to complete the solution to Siegel's famous problem on hyperbolic lattices, and offers further substantive advances to address the quite complicated analytic and topological properties of hyperbolic orbifolds. Our novel approach is to use a fundamental result concerning spaces of finitely generated Kleinian groups: they are closed in the topology of algebraic convergence. Indeed in this is also true in higher dimensions when fairly minor additional (and necessary) conditions are imposed - for instance giving a uniform bound on the torsion in a sequence, or asking that the limit set be in geometric position. In fact this property (which is basically a consequence of the existence of Zassenhaus neighbourhoods for semi-simple Lie groups) holds more generally for groups of isometries of negatively curved metrics because of the Margulis-Gromov lemma
How does the domino effect Abu Dhabi's urbanization and climate change impact the mangroves? In this thesis we be focusing on the potential impact of urbanization and that of global change on the case study of the Eastern Mangrove National Park, Abu Dhabi. As we live in the city of Abu Dhabi, UAE that has rapidly urbanized and claimed its importance in trade after only becoming an independent sovereign state in 1971. This means that the city has changed from a nomadic lifestyle to one that is highly urbanized, this puts pressure on the natural environment and its protection. Along with an international case study of the mangroves in Vietnam, we will be able to know the status of the mangroves in both locations, be able to compare their condition and protection methods through studying legislations, policies and other means of protection to sustain the natural reserve.
Business excellence is about achieving and sustaining an outstanding level of performance that exceeds the current and future needs and expectations of the entity's stakeholders. Business excellence evolved from the Concept of the total quality management (TQM) that was firstly formed and conceptualized in the early 1980's (Deming 1986 and Juran 1986). There is no consensus on the key constructs of total quality management (TQM) and business excellence, therefore, there is no unified and universally accepted approach to measure the impact of implementing total quality management (TQM) and business excellence on the financial and nonfinancial performance of the organizations (Santos-Vijande and Alvarez-Gonzalez 2007). The nature of nuclear industry makes it very challenging to adopt and harness innovation management practices. Still, one key element of the EFQM business excellence model implemented by Emirates Nuclear Energy Corporation (ENEC) is learning and innovation. Harnessing innovation and creativity is also one of the eight fundamental concepts of business excellence (EFQM 2013). This study will investigate the impact of implementing business excellence models on the innovation maturity in the Emirates Nuclear Energy Corporation (ENEC).
Chlorophenols are considered hazardous pollutants due to their negative health effects such as carcinogenicity, thus the water contaminated by chlorophenols should be treated before discharged to the environment. Investigating the applications of Ionic Liquids (ILs) as green solvents in water treatment is important regarding their advantageous properties over organic solvents such as low vapor pressure and non-flammability. In this study, the extraction of 2,4, 6- Trichlorophenol (TCP) and Pentachlorophenol (PCP) from aqueous solution using six hydrophobic ILs was investigated. Results showed that the highest extraction efficiency for both TCP and PCP were 94.0% and 93.6% respectively,when 1-ethyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide ([1,3emPY][Tf2N])was used as extractant. This indicates the promising application of [1,3emPY][Tf2N] in wastewater treatment.
The paper investigates the phenomenon of wasta in the UA and its use by women to get career advancement. As wasta takes an essential role in the culture and social life of the Emirati people, it is present in many aspects of professional life. The study aims at discussing the main aspects of wasta, its use in the professional life, the problem of wasta in the UAE, and its impact on organizational development. Secondary data analysis has enabled to collect the data for analysis and provide proper conclusions. It has been found that wasta has numerous negative impacts not only on organizational development, but on the economic development of the country. It is suggested that a meritocratic approach can help to deal with the issue wasta. Finally, it is recommended to conduct a further research to analyze the wasta use in different organizational structures
This paper proposed two new lane changing strategies for connected vehicles using cooperative game theory: the transferable utility strategy which allows side payment from one vehicle to another and the non-transferable utility strategy using Nash bargaining solution. When a side payment is allowed, a monetary payment from one vehicle to another is needed to achieve the solution. In this case, vehicles are actually making transactions on the right-of-way: they may have a chance to buy time from other vehicles at a reasonable price that satisfies both. For vehicles that are not willing to participate in transactions, Nash bargaining solution achieves a Pareto efficiency and ensures that no lane resource is wasted. Simulations using cellular automata showed that, cooperation between drivers could help achieve a win-win result. Besides, a properly designed utility function could encourage vehicles to participate in transactions, and prevent them from cheating in their value of time.
Automated vehicle technique makes the car-following model cannot only be used in simulation as a description of real world, but also applied as a technical support in real world. As field application requires high level of safety, safety design in car-following model for automated driving environment becomes more important than in traditional simulation-only model. This paper presented a safety-oriented car-following model for connected automated vehicles, considering their different delays and unique information broadcasting features. The dynamic resistance, friction and propulsion were considered when formulating the vehicle's motion equation, and possible packet loss was also included. Simulation in urban road & highway scenario using the field data of connected vehicles from Ann Arbor, Michigan showed that the model can guarantee safety in different driving environments. Besides, it also demonstrated high efficiency and good stability.
