1,287 research outputs found
Development of PAN (personal area network) for Mobile Robot Using Bluetooth Transceiver
In recent years, wireless applications using radio frequency (RF) have been rapidly evolving in personal computing and communications devices. Bluetooth technology was created to replace the cables used on mobile devices. Bluetooth is an open specification and encompasses a simple low-cost, low power solution for integration into devices. This research work aim was to provide a PAN (personal area network) for computer based mobile robot that supports real-time control of four mobile robots from a host mobile robot. With ad hoc topology, mobile robots may request and establish a connection when it is within the range or terminated the connection when it leaves the area. A system that contains both hardware and software is designed to enable the robots to participate in multi-agent robotics system (MARS). Computer based mobile robot provide operating system that enabled development of wireless connection via IP address
Separable Structure of Many-Body Ground-State Wave Function
We have investigated a general structure of the ground-state wave function
for the Schr\"odinger equation for identical interacting particles (bosons
or fermions) confined in a harmonic anisotropic trap in the limit of large .
It is shown that the ground-state wave function can be written in a separable
form. As an example of its applications, this form is used to obtain the
ground-state wave function describing collective dynamics for trapped
bosons interacting via contact forces.Comment: J. Phys. B: At. Mol. Opt. Phys. 33 (2000) (accepted for publication
Semi-device-independent bounds on entanglement
Detection and quantification of entanglement in quantum resources are two key
steps in the implementation of various quantum-information processing tasks.
Here, we show that Bell-type inequalities are not only useful in verifying the
presence of entanglement but can also be used to bound the entanglement of the
underlying physical system. Our main tool consists of a family of
Clauser-Horne-like Bell inequalities that cannot be violated maximally by any
finite-dimensional maximally entangled state. Using these inequalities, we
demonstrate the explicit construction of both lower and upper bounds on the
concurrence for two-qubit states. The fact that these bounds arise from
Bell-type inequalities also allows them to be obtained in a
semi-device-independent manner, that is, with assumption of the dimension of
the Hilbert space but without resorting to any knowledge of the actual
measurements being performed on the individual subsystems.Comment: 8 pages, 2 figures (published version). Note 1: Title changed to
distinguish our approach from the standard device-independent scenario where
no assumption on the Hilbert space dimension is made. Note 2: This paper
contains explicit examples of more nonlocality with less entanglement in the
simplest CH-like scenario (see also arXiv:1011.5206 by Vidick and Wehner for
related results
Better Bell Inequality Violation by Collective Measurements
The standard Bell inequality experiments test for violation of local realism
by repeatedly making local measurements on individual copies of an entangled
quantum state. Here we investigate the possibility of increasing the violation
of a Bell inequality by making collective measurements. We show that
nonlocality of bipartite pure entangled states, quantified by their maximal
violation of the Bell-Clauser-Horne inequality, can always be enhanced by
collective measurements, even without communication between the parties. For
mixed states we also show that collective measurements can increase the
violation of Bell inequalities, although numerical evidence suggests that the
phenomenon is not common as it is for pure states.Comment: 7 pages, 4 figures and 1 table; references update
Quantum interference from sums over closed paths for electrons on a three-dimensional lattice in a magnetic field: total energy, magnetic moment, and orbital susceptibility
We study quantum interference effects due to electron motion on a
three-dimensional cubic lattice in a continuously-tunable magnetic field of
arbitrary orientation and magnitude. These effects arise from the interference
between magnetic phase factors associated with different electron closed paths.
The sums of these phase factors, called lattice path-integrals, are
``many-loop" generalizations of the standard ``one-loop" Aharonov-Bohm-type
argument. Our lattice path integral calculation enables us to obtain various
important physical quantities through several different methods. The spirit of
our approach follows Feynman's programme: to derive physical quantities in
terms of ``sums over paths". From these lattice path-integrals we compute
analytically, for several lengths of the electron path, the half-filled
Fermi-sea ground-state energy of noninteracting spinless electrons in a cubic
lattice. Our results are valid for any strength of the applied magnetic field
in any direction. We also study in detail two experimentally important
quantities: the magnetic moment and orbital susceptibility at half-filling, as
well as the zero-field susceptibility as a function of the Fermi energy.Comment: 14 pages, RevTe
Effectiveness of State Trading Enterprises in Achieving Food Security: Case Studies from Bernas in Malaysia and Bulog in Indonesia
The issue of food security is of vital concern to many developing countries and various kinds of policy instruments have been employed to achieve stable food sources for growing demands. One of the most predominant policy instruments in both the developed and developing world involves centralised state trading through what are called State Trading Enterprises (STEs). State trading
is more prevalent in the agriculture industry as countries utilise these entities as a means to achieve agricultural policy objectives such as stabilising domestic prices, eliminating marketing inefficiencies and ensuring the availability of food supplies (WTO, 1995). STEs are therefore often an integral aspect of a policy package implemented to address the challenges in achieving the food security objectives of a country. However, although these entities are recognised as an instrument for addressing market challenges, STEs have also been criticised for their distortion of trade and markets through the monopolistic power and government support. Therefore, it is necessary to assess the effectiveness of STEs at achieving the objective of food security, as well as consider the potential market distortions that arise with STEs and the common policies associated with them.
This report brings together insights from two STEs in Southeast Asia, namely Bernas in Malaysia and Bulog in Indonesia. Each study offers a historical perspective to the financial, economic and social contributions of the STEs, their effectiveness in achieving the domestic food security agenda and several policy suggestions to mitigate the issues within each country. This report will
be broken down as follows:
• The first part of this report introduces the case studies by looking into state trading enterprises, food security and the contextual backgrounds of Malaysia and Indonesia’s agricultural policies;
• The second portion will present the country case studies that are designed to analyse how state trading enterprises and their associated food-related policies have affected the agriculture and food trade sectors in Malaysia and Indonesia;
• Finally, the report will conclude with a summary of the country case study findings and the implications for agriculture and food trade policies in other developing countries
Important Parameters for Hand Function Assessment of Stroke Patients
Clinical scales such as Fugl-Meyer Assessment and Motor Assessment Scale are widely used to evaluate stroke patient's motor performance. However, the scoring systems of these assessments provide only rough estimation, making it difficult to objectively quantify impairment and disability or even rehabilitation progress throughout their rehabilitation period. In contrast, robot-based assessments are objective, repeatable, and could potentially reduce the assessment time. However, robot-based assessment scales are not as well established as conventional assessment scale and the correlation to conventional assessment scale is unclear. This paper discusses the important parameters in order to assess the hand function of stroke patients. This knowledge will provide a contribution to the development of a new robot-based assessment device effectively by including the important parameters in the device. The important parameters were included in development of iRest and yielded promising results that illustrate the potential of the important parameters in assessing the hand function of stroke patients
Bounds on Quantum Correlations in Bell Inequality Experiments
Bell inequality violation is one of the most widely known manifestations of
entanglement in quantum mechanics; indicating that experiments on physically
separated quantum mechanical systems cannot be given a local realistic
description. However, despite the importance of Bell inequalities, it is not
known in general how to determine whether a given entangled state will violate
a Bell inequality. This is because one can choose to make many different
measurements on a quantum system to test any given Bell inequality and the
optimization over measurements is a high-dimensional variational problem. In
order to better understand this problem we present algorithms that provide, for
a given quantum state, both a lower bound and an upper bound on the maximal
expectation value of a Bell operator. Both bounds apply techniques from convex
optimization and the methodology for creating upper bounds allows them to be
systematically improved. In many cases these bounds determine measurements that
would demonstrate violation of the Bell inequality or provide a bound that
rules out the possibility of a violation. Examples are given to illustrate how
these algorithms can be used to conclude definitively if some quantum states
violate a given Bell inequality.Comment: 13 pages, 1 table, 2 figures. Updated version as published in PR
Strongly Localized Electrons in a Magnetic Field: Exact Results on Quantum Interference and Magnetoconductance
We study quantum interference effects on the transition strength for strongly
localized electrons hopping on 2D square and 3D cubic lattices in a magnetic
field B. In 2D, we obtain closed-form expressions for the tunneling probability
between two arbitrary sites by exactly summing the corresponding phase factors
of all directed paths connecting them. An analytic expression for the
magnetoconductance, as an explicit function of the magnetic flux, is derived.
In the experimentally important 3D case, we show how the interference patterns
and the small-B behavior of the magnetoconductance vary according to the
orientation of B.Comment: 4 pages, RevTe
Generating nonclassical correlations without fully aligning measurements
We investigate the scenario where spatially separated parties perform
measurements in randomly chosen bases on an N-partite
Greenberger-Horne-Zeilinger state. We show that without any alignment of the
measurements, the observers will obtain correlations that violate a Bell
inequality with a probability that rapidly approaches 1 as N increases and that
this probability is robust against noise. We also prove that restricting these
randomly chosen measurements to a plane perpendicular to a common direction
will always generate correlations that violate some Bell inequality.
Specifically, if each observer chooses their two measurements to be locally
orthogonal, then the N observers will violate one of two Bell inequalities by
an amount that increases exponentially with N. These results are also robust
against noise and perturbations of each observer's reference direction from the
common direction.Comment: v2: Essentially published version (with typos fixed, results updated
in Table 2 and Figure 4 replaced); v1: 16 pages, 5 figures, 2 tables,
comments welcom
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