759 research outputs found
Cooling of a Nanomechanical Resonator in the Presence of a Single Diatomic Molecule
We propose a theoretical scheme for coupling a nanomechanical resonator to a
single diatomic molecule via microwave cavity mode of a driven LC resonator. We
describe the diatomic molecule by a Morse potential and find the corresponding
equations of motion of the hybrid system by using Fokker-Planck formalism.
Analytical expressions for the effective frequency and the effective damping of
the nanomechanical resonator are obtained. We analyze the ground state cooling
of the nanomechanical resonator in presence of the diatomic molecule. The
results confirm that presence of the molecule improves the cooling process of
the mechanical resonator. Finally, the effect of molecule's parameters on the
cooling mechanism is studied.Comment: 10 pages, 8 figure
Generating quantum discord between two distant Bose-Einstein condensates with Bell-like detection
We propose a technique that enables the creation of quantum discord between
two distant nodes, each containing a cavity consist of the Bose-Einstein
condensate, by applying a non-ideal Bell-like detection on the output modes of
optical cavities. We find the covariance matrix of the system after the
non-ideal Bell-like detection, showing explicitly that one enables manipulation
of the quantum correlations, and particularly quantum discord, between remote
Bose-Einstein condensates. We also find that the non-ideal Bell-like detection
can create entanglement between distant Bose-Einstein condensates at the two
remote site
Mutual information as an order parameter for quantum synchronization
Spontaneous synchronization is a fundamental phenomenon, important in many
theoretical studies and applications. Recently this effect has been analyzed
and observed in a number of physical systems close to the quantum mechanical
regime. In this work we propose the mutual information as a useful order
parameter which can capture the emergence of synchronization in very different
contexts, ranging from semi-classical to intrinsically quantum mechanical
systems. Specifically we first study the synchronization of two coupled Van der
Pol oscillators in both classical and quantum regimes and later we consider the
synchronization of two qubits inside two coupled optical cavities. In all these
contexts, we find that mutual information can be used as an appropriate figure
of merit for determining the synchronization phases, independently of the
specific details of the system
Processing and performance of compounds based on emulsion/solution SBRs
Solution and emulstion SBRs are both widely used in tire industry. But which method offers the industry the best solution
Modeling and Control of a Smart Single-Layer Graphene Sheet
In this study, a smart single-layer graphene sheet (SLGS) is analytically modeled and its buckling is controlled using coupled polyvinylidene fluoride (PVDF) nanoplates. A voltage is applied to the PVDF nanoplate in thickness direction in order to control the critical load of the SLGS. Electric potential distribution is assumed as a combination of a half-cosine and linear variation in order to satisfy the Maxwell equation. The exact analysis is performed for the case when all four ends are simply supported and in free electrical boundary condition. The nonlocal governing equations are derived through Hamilton’s principle and energy method based on a nonlocal Mindlin plate theory. The detailed mathematical derivations are presented and numerical investigations are performed, while the emphasis is placed on investigating the effect of several parameters such as small-scale coefficient, stiffness of the internal elastic medium, graphene length, mode number, and external electric voltage on the buckling smart control of the SLGS in detail. It is explicitly shown that the imposed external voltage is an effective controlling parameter for buckling of the SLGS. Numerical results are presented to serve as benchmarks for design and smart control of nanodevices
Job Involvement and Organizational Commitment of Employees of Prehospital Emergency Medical System
Background: Several studies are available on organizational commitment of employees in different organizations. However, the organizational commitment and job involvement of the employees in the prehospital emergency medical system (PEMS) of Iran have largely been ignored.
Objectives: This study aimed to investigate the organizational commitment and job involvement of the employees of PEMS and the relationship between these two issues.
Materials and Methods: This cross-sectional study was conducted on 160 employees of Kashan PEMS who were selected through a census method in 2014. A 3-part instrument was used in this study, including a demographic questionnaire, the Allen and Miller’s organizational commitment inventory, and the Lodahl and Kejner’s job involvement inventory. We used descriptive statistics, Spearman correlation coefficient, Kruskal-Wallis, Friedman, analysis of variance, and Tukey post hoc tests to analyze the data.
Results: The mean job involvement and organizational commitment scores were 61.78 ± 10.69 and 73.89 ± 13.58, respectively. The mean scores of job involvement and organizational commitment were significantly different in subjects with different work experiences (P = 0.043 and P = 0.012, respectively). However, no significant differences were observed between the mean scores of organizational commitment and job involvement in subjects with different fields of study, different levels of interest in the profession, and various educational levels. A direct significant correlation was found between the total scores of organizational commitment and job involvement of workers in Kashan PEMS (r = 0.910, P < 0.001).
Conclusions: This study showed that the employees in the Kashan PEMS obtained half of the score of organizational commitment and about two-thirds of the job involvement score. Therefore, the higher level managers of the emergency medical system are advised to implement some strategies to increase the employees’ job involvement and organizational commitment
Applying job hazard analysis and William Fine methods on risks identification and assessment of jobs in hot rolling steel, Iran
Background and purpose: Comprehensive evaluation of jobs in industries is a practical and effective method that could identify the jobs and industries with negative effects on the environment. This study identified environmental hazards of hot rolling process and assessing their risks. Materials and methods: An observational study was carried out in which identification of human activity and job’s risks in production hall of Kavir Steel Complex was done according to ISO 14001 approaches (pollutant emissions to air, discharges to water, energy consumption, energy released as heat, wastes, side products, etc) by Job Hazard Analysis method (JHA). Then the risks identified were prioritized and assessed using William Fine method. Results: We identified 205 environmental hazards (in 9 groups) associated with production personnel (n= 81), mechanics and maintenance personnel (n= 44), bed personnel (n= 9), personnel of cleaning services (n= 33), and water plant personnel (n= 38). The highest and lowest rate of risks were due to creation and distribution of wastes (n= 73) and corrosion and depreciation of equipment, (n= 1), respectively. Conclusion: The production personnel were mainly responsible for environmental emissions. The leading causes were stress and anxiety about stoppage of production, payment reduction, and lack of awareness and workers and supervisors on environmental issues. © 2017, Mazandaran University of Medical Sciences. All rights reserved
Electro-Thermo-Mechanical Vibration Analysis of a Foam-Core Smart Composite Cylindrical Shell Containing Fluid
ABSTRACT In this study, free vibration of a foam-core orthotropic smart composite cylindrical shell (SCCS) filled with a non-viscous compressible fluid, subjected to combined electro-thermo-mechanical loads is investigated. Piezoelectric polymeric cylindrical shell, is made from polyvinylidene fluoride (PVDF) and reinforced by armchair double walled boron nitride nanotubes (DWBNNTs). Characteristics of the equivalent composite are determined using micro-electro-mechanical models. The poly ethylene (PE) foam-core is modeled based on Winkler and Pasternak foundations. Employing the charge equation for coupling electrical and mechanical fields, the problem is turned into an eigenvalue one, for which analytical frequency equations are derived considering free electrical and simply supported mechanical boundary conditions at circular surfaces at either ends of the cylindrical shell. The influence of electric potential generated, filledfluid, orientation angle of DWBNNTs, foam-core and a few other parameters on the resonance frequency of SCCS are investigated. Results show that SCCS and consequently the generated Φ improve sensor and actuator applications in several process industries, because it not only increases the vibration frequency, but also extends economic viability of the smart structure
Effect of Motor Imagery Training with Sensory Feedback on Sensory-Motor Function of the Upper Extremity in Patients with Chronic Stroke
BACKGROUND AND OBJECTIVE: Conventional rehabilitation in stroke patients is more likely to use repetitive movements to improve motor function, which may be difficult for people with motor limitations. Mental imagery training can be done without moving the affected limbs, and this method is safe, cheap and accessible. The aim of this study is to investigate the effect of motor imagery training with sensory feedback on sensory-motor function of the upper extremity in patients with chronic stroke.
METHODS: In this non-randomized clinical trial, 30 stroke patients with level of upper extremity function according to Brunnsrom’s recovery ≥ 2, and cognitive function level according to MMSE ≥ 21 were selected through non-probability sampling from rehabilitation centers and randomly divided into intervention and control groups. Patients in the control group received conventional rehabilitation programs, and patients in the intervention group received motor imagery training with sensory feedback in 12 sessions (45 – 60 minutes), in addition to conventional rehabilitation programs. Before and after the interventions, sensory and motor functions were assessed using Box-Block test, Purde-Pegbord test, range of motion, FMA-UE total and FMA-UE coordination/speed, 2-point-discrimination, Nottingham-Sensory Assessment, Modified-Ashworth Scale and Stroke Impact Scale.
FINDINGS: Mean percentage of changes in motor function and speed/coordination of upper extremity, shoulder and elbow range of motion and gross dexterity was higher in the interventional group (50%, 50%, 80%, 50% and 80%, respectively) compared with the conventional rehabilitation group (20%, 18%, 50%, 30% and 30%, respectively) (p≤0.05). However, both interventions had similar effect on sensory function, fine dexterity, muscle tone and activities of daily living.
CONCLUSION: The results of the study showed that motor imagery training with sensory feedback along with conventional rehabilitation could enhance the motor function, gross dexterity and range of motion of the upper extremity in chronic stroke patients
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