399 research outputs found

    Navigation control of an automated mobile robot robot using neural network technique

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    Over recent years, automated mobile robots play a crucial role in various navigation operations. For any mobile device, the capacity to explore in its surroundings is essential. Evading hazardous circumstances, for example, crashes and risky conditions (temperature, radiation, presentation to climate, and so on.) comes in the first place, yet in the event that the robot has a reason that identifies with particular places in its surroundings, it must discover those spots. There is an increment in examination here due to the requisition of mobile robots in a solving issues like investigating natural landscape and assets, transportation tasks, surveillance, or cleaning. We require great moving competencies and a well exactness for moving in a specified track in these requisitions. Notwithstanding, control of these navigation bots get to be exceptionally troublesome because of the exceedingly unsystematic and dynamic aspects of the surrounding world. The intelligent reply to this issue is the provision of sensors to study the earth. As neural networks (NNs) are described by adaptability and a fitness for managing non-linear problems, they are conceived to be useful when utilized on navigation robots. In this exploration our computerized reasoning framework is focused around neural network model for control of an Automated motion robot in eccentric and unsystematic nature. Hence the back propagation algorithm has been utilized for controlling the direction of the mobile robot when it experiences by an obstacle in the left, right and front directions. The recreation of the robot under different deterrent conditions is carried out utilizing Arduino which utilizes C programs for usage

    Ultrabroadband Nonlinear Optics in Nanophotonic Periodically Poled Lithium Niobate Waveguides

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    Quasi-phasematched interactions in waveguides with quadratic nonlinearities enable highly efficient nonlinear frequency conversion. In this article, we demonstrate the first generation of devices that combine the dispersion-engineering available in nanophotonic waveguides with quasi-phasematched nonlinear interactions available in periodically poled lithium niobate (PPLN). This combination enables quasi-static interactions of femtosecond pulses, reducing the pulse energy requirements by several orders of magnitude, from picojoules to femtojoules. We experimentally demonstrate two effects associated with second harmonic generation. First, we observe efficient quasi-phasematched second harmonic generation with <100 fJ of pulse energy. Second, in the limit of strong phase-mismatch, we observe spectral broadening of both harmonics with as little as 2-pJ of pulse energy. These results lay a foundation for a new class of nonlinear devices, in which co-engineering of dispersion with quasi-phasematching enables efficient nonlinear optics at the femtojoule level

    Design of a continuous-wave tunable terahertz source using waveguide-phase-matched GaAs

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    A novel source of continuous-wave terahertz radiation based on difference frequency generation (DFG) in GaAs crystal is proposed. Phase matching is provided using integration of appropriate optical and terahertz waveguides based on dispersive properties of GaAs. The output frequency can be tuned between 0–3.5 THz by tuning the incident wavelengths in the range of 1.5–1.6 µm

    Proposal for Compact Optical Filters Using Large Index Step Binary Supergratings

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    Compact optical filters are proposed using an aperiodic grating of fixed element size [i.e., a binary supergrating (BSG)] with a large refractive index step. These filters allow for almost arbitrary wavelength filtering, yet they are more compact than previous demonstrations of BSG. The filters are designed using a combination of Boolean particle swarm optimization (B-PSO) and a one-dimensional transfer matrix method. To demonstrate the compact device size, several 50-mum-long single-wavelength transmission filters are demonstrated theoretically, each having a different wavelength while using the same structural parameters. A multiwavelength filter is also proposed in an 80-mum-long structure to show the versatility of the large refractive index step BSG. A genetic algorithm is substituted for the B-PSO; however, B-PSO shows better performance here. This work may be applied to produce compact optical filters for intrachip optical networks and compact tunable lasers, while using existing single-step photolithography processes

    Realizing Spin-Hamiltonians in Nanolaser Lattices

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    We demonstrate both theoretically and experimentally that coupled metallic nanolasers can be used to emulate spin-Hamiltonians. Depending on the geometry of the array, we observe ferromagnetic and antiferromagnetic behaviors, as well as geometric frustration

    Panoramic-Based Mandibular Indices and Bone Mineral Density of Femoral Neck and Lumbar Vertebrae in Women

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    Objective: The aim of this cross-sectional analytic study was to evaluate the diagnostic efficacy of panoramic-based indices of the mandible (Mental Index-MI, Mandibular Cortical Index-MCI and Panoramic Mandibular Index-PMI) and to determine their correlationwith bone mineral density (BMD) of the femoral neck and lumbar vertebrae (L2-L4) in order to assess the possibility of using these parameters as indicators of osteoporosis.Materials and Methods: The mandibular indices of 67 women over 35 years old were measured from panoramic radiographs, and bone densitometry was performed in the femoral neck and lumbar vertebrae (L2-L4), using DXA (Dual Energy X-ray Absorptiometry)technique. The patients were divided into three categories of normal, osteopenic andosteoporotic in each skeletal region. One-way ANOVA and ROC curve analyses were applied.The results were considered statistically significant when the P-value was less than 0.05.Results: Comparing the mean BMD in the femoral neck in women between C1 and C3 subgroups of MCI, a significant difference was detected (P=0.04). The mean PMI in the three skeletal subgroups was not different according to the skeletal region (P>0.05). We found a significant difference in mean MI between normal and osteopenic subgroups in the femoral neck (P=0.042).Conclusion: Using radiomorphometric indices of the mandible (MCI-MI) may be useful in determining the skeletal status of the patients, but is not sufficient for precise evaluation

    Ionic mass transfer at point electrodes located at cathode support plate in an electrorefining cell in presence of rectangular turbulent promoters

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    Current density plays a major role in deciding the plant size, current efficiency, and energy consumption in electrorefining cells. In general, operating current density will be 40% of the limiting current density. Forced circulation of the electrolyte in the presence of promoters improves the mass transfer coefficient. In the present study, rectangular turbulence promoters are fitted at the bottom side of the cell to improve the mass transfer coefficient at the cathode support plate. The limiting current density technique is used to measure the mass transfer coefficient. The variables covered in the present study are the effects of flow rate, promoter height, and spacing among the promoters. The electrolyte consists of copper sulfate and sulphuric acid. At a regulated flow rate, the electrolyte is pumped from the recirculation tank to the cell through an intermediate overhead tank. The limiting current density increased with an increasing flow rate in the presence of promoters, and thus the overall mass transfer coefficient on the cathode support plate also improved. With an increase in the flow rate of the electrolyte from 6.67 × 10−6 to 153.33 m3/s, limiting current density increased from 356.8 to 488.8 A/m2 for spacing of 0.30 m, with a promoter height of 0.01 m. However, it is noteworthy that when the promoter height is increased from 0.01 to 0.07 m, the overall mass transfer coefficient is found to increase up to 60%, but with the further increase in the promoter height to 0.30 m the mass transfer coefficient starts to decrease. Therefore, the optimized cell parameters are established in this work. The current sustainable concept of employing rectangular turbulence promoters will bring benefits to any precious metal refining or electrowinning tank house electrolytes

    Evaluation of response to preoperative chemotherapy versus surgery alone in gastroesophageal cancer: Tumor resectability, pathologic results and post-operative complications

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    Gastroesophageal cancer is one of the most common types of cancer worldwide. Despite significant developments in management, 5-year survival in the developing world is less than 20 percent. Due to restricted research about the impact of preoperative chemotherapy (POC) on tumor resection, pathological response and postoperative complications in Iran, we designed and implemented the present retrospective cross- sectional study on 156 patients with gastroesophageal cancer (GEc) between 2013 and 2015 at Shariati Hospital of Tehran. Two groups were included, the first group had previously received preoperative chemotherapy and the second group had only undergone surgery. All patients were followed for at least one year after the operation in terms of tumor recurrence, relapse free survival and one-year survival. The two groups were eventually compared regarding tumor resection, pathological response, postoperative complications, recurrence rate and survival. The mean age was 66.5± 7.3 years and 78 percent were male. The tumor resectability, pathological response and postoperative complications in the group which received POC were 93.5, 21.8 and 12.8, respectively, and in the surgery alone group figures for tumor resection and postoperative complications were 76 and 29.5, respectively. Also based on our study the 5-year survival in the POC group was better (79.5 vs. 66.5). Using standard neoadjuvant regimens (preoperative chemotherapy/ chemoradiotherapy) beforesurgery could increase tumor resectability, pathological response, and improve the general status of the patients. Therefore using POC may be recommended over surgery alone. © 2016, Asian Pacific Journal of Cancer Prevention

    Correlation of Clinical Examination, MRI and Arthroscopy Findings in Menisco-Cruciate Injuries of the Knee: A Prospective Diagnostic Study

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    Background: The aim of this study was to examine the correlation of the clinical examination, MRI and arthroscopic findings in cruciate ligaments and meniscal injuries of knee and to evaluate the accuracy of clinical examination and MRI with the gold standard arthroscopy. Methods: A prospective diagnostic double-blind study was conducted on 104 consecutive patients admitted to the outdoor/casualty with trauma to the knee complaining of knee pain/locking/ instability, from August 2012 to June 2014. All the patients were subjected to clinical examination, MRI scanning and diagnostic arthroscopy. Variables like sensitivity, specificity, positive predictive value, negative predictive value and accuracy of clinical examination and MRI against arthroscopy were evaluated. Results: The sensitivity, specificity and accuracy of clinical examination for anterior cruciate ligament tears were 94.7%, 71.4% and 88.5% and for MRI were 94.7%, 78.6% and 90.4%, respectively; for posterior cruciate ligament tears 100%, 100% and 100% for clinical examination and for MRI 80%, 97.9% and 96.2%, respectively. These values for medial meniscus tears were 76.5%, 68.6% and 71.2% for clinical examination and 88.2%, 62.8% and 71.2% respectively for MRI. For lateral meniscus tears, 40%, 94.6% and 78.8% for clinical examination and 46.7%, 89.2% and 76.9% respectively for MRI. Conclusions: A skillfully performed clinical examination establishes a diagnosis on which an arthroscopic procedure can be planned, reserving MRI scans for patients where the clinical examination fails to establish a diagnosis or cannot be performed. Decision to use MRI should be based on the criteria that it would confirm, expand the diagnosis or change diagnosis in such a way that alters the proposed treatment
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