1,697 research outputs found

    Long Memory in the Australian Stock Market

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    In this paper, we re-examine the evidence of long memory in the Australian stock market. Using the rescaled range analysis, we find evidence of long memory and non-periodic cycles in the All Ordinaries Index. The result suggests that long memory is present in the Australian stock market. Furthermore, we add to the literature by investigating the presence of long memory in the daily ASX 50 index and its 50 constituent stocks using a GPH test proposed by Geweke and Porter-Hudak (1983). The results of individual stocks differ from those of the ASX 50 index and suggest that a common stock index is not representative of all market features.long memory, persistence, rescaled range analysis, GPH test

    Sequence Based Optimization of Manufacturing Complexity in a Mixed Model Assembly Line

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    Increasing production variability while maintaining operation efficiency remains a critical issue in many manufacturing industries. While the adoption of mixed-model assembly lines enables the production of high product variety, it also makes the system more complex as variety increases. This paper proposes an information entropy-based methodology that quantifies and then minimizes the complexity through product sequencing. The theory feasibility is demonstrated in a series of simulations to showcase the impact of sequencing in controlling the system predictability and complexity. Hence, the framework not only serves as a tool to quantitatively assess the impact of complexity on total system performance but also provides means and insights into how complexity can be mitigated without affecting the overall manufacturing workload

    Circuit Structure and Control Method to Reduce Size and Harmonic Distortion of Interleaved Dual Buck Inverter

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    A new circuit structure and control method for a high power interleaved dual-buck inverter are proposed. The proposed inverter consists of six switches, four diodes and two inductors, uses a dual-buck structure to eliminate zero-cross distortion, and operates in an interleaved mode to reduce the current stress of switch. To reduce the total harmonic distortion at low output power, the inverter is controlled using discontinuous-current-mode control combined with continuous-current-mode control. The experimental inverter had a power-conversion efficiency of 98.5% at output power = 1300 W and 98.3% at output power = 2 kW, when the inverter was operated at an input voltage of 400 V-DC, output voltage of 220 V-AC/60 Hz, and switching frequency of 20 kHz. The total harmonic distortion was < 0.66%, which demonstrates that the inverter is suitable for high-power dc-ac power conversion.11Ysciescopu

    Topological Domain-Wall States Hosting Quantized Polarization and Majorana Zero Modes Without Bulk Boundary Correspondence

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    Bulk-boundary correspondence is a concept for topological insulators and superconductors that determines the existence of topological boundary states within the tenfold classification table. Contrary to this belief, we demonstrate that topological domain-wall states can emerge in all forbidden 1D classes in the classification table using representative generalized Su-Schrieffer-Heeger and Kitaev models, which manifests as quantized electric dipole moments and Majorana zero modes, respectively. We first show that a zero-energy domain-wall state can possess a quantized polarization, even if the polarization of individual domains is not inherently quantized. A quantized Berry phase difference between the domains confirms the non-trivial nature of the domain-wall states, implying a general-bulk-boundary principle, further confirmed by the tight-binding, topological field, and low-energy effective theories. Our methodology is then extended to a superconducting system, resulting in Majorana zero modes on the domain wall of a generalized Kitaev model. Finally, we suggest potential systems where our results may be realized, spanning from condensed matter to optical

    Efficient Acceleration-Level Formula of Bias Acceleration Satisfying Time Precedence for Operational Space Formulation

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    Operational space formulation has been used for robots to perform multi-tasks by taking advantage of dynamic consistency. Bias acceleration, which is an acceleration realized right after applying the control torque to a robot, compensates for the acceleration due to the higher priority tasks, thereby achieving the goal of the tasks with lower priority. Since the operational space formulation requires many computations during real-time control, there is a strong need to reduce the number of computations. We proposed an efficient acceleration-level bias acceleration formula while showing that the original bias acceleration formula could take 30-50% of the total computation for the operational space formulation. Moreover, we clarified the underlying time precedence of bias acceleration, which was implicitly provided in the original formula but was never clearly explained. Further, we have proved that the inefficiency of the original formula is due to the use of unnecessary full robot dynamics, the use of which is almost entirely eliminated in the proposed formula. Through extensive simulations and experiments, we have verified that the proposed formula needs 2-4% computations of the original, is independent of the Coriolis/centrifugal torque and the gravity torque, and is equivalent to the original formula. We expect that, with a deeper understanding of the bias acceleration, the proposed bias acceleration formula could promote the use of high degrees-of-freedom robots

    Vertically aligned InGaN nanowires with engineered axial In composition for highly efficient visible light emission.

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    We report on the fabrication of novel InGaN nanowires (NWs) with improved crystalline quality and high radiative efficiency for applications as nanoscale visible light emitters. Pristine InGaN NWs grown under a uniform In/Ga molar flow ratio (UIF) exhibited multi-peak white-like emission and a high density of dislocation-like defects. A phase separation and broad emission with non-uniform luminescent clusters were also observed for a single UIF NW investigated by spatially resolved cathodoluminescence. Hence, we proposed a simple approach based on engineering the axial In content by increasing the In/Ga molar flow ratio at the end of NW growth. This new approach yielded samples with a high luminescence intensity, a narrow emission spectrum, and enhanced crystalline quality. Using time-resolved photoluminescence spectroscopy, the UIF NWs exhibited a long radiative recombination time (τr) and low internal quantum efficiency (IQE) due to strong exciton localization and carrier trapping in defect states. In contrast, NWs with engineered In content demonstrated three times higher IQE and a much shorter τr due to mitigated In fluctuation and improved crystal quality

    Return and Volatility Transmission Between Oil Prices and Emerging Asian Markets

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    We investigated return and volatility transmission between oil futures prices and ten Asian emerging indices using a VAR-bivariate GARCH model. We also analyzed the optimal weights and hedge ratios for optimizing portfolios to minimize the exposure to risk associated with oil futures price changes. We found no significant influence of oil futures price returns on Asian stock returns. However, strong volatility spillover was observed from oil futures price shocks and volatility to counterpart volatilities. In addition, optimal weights and hedge ratios suggested that incorporating the oil asset in a well-diversified portfolio effectively hedged the risks associated with oil price volatility

    Minimum Surgico-Orthopedic Treatment using Computer-Assisted Single-Tooth Osteotomy in an Adolescent Skeletal Class III Patient with Anterior Ankylosed Tooth: A Case Report

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    Traumatic tooth avulsion can lead to ankylosis, which may interfere with growth of the alveolar bone in a growing patient. The resulting difference in alveolar bone height and position can lead to esthetic problems such as open bite.A growing 13-year-old female patient presented skeletal Class III malocclusion with bone ankylosis of a maxillary anterior tooth. Even after 2 years of orthopedic and orthodontic treatment, little improvement was achieved regarding the positions of the anterior maxillary teeth, or the vertical position of the maxillary right central incisor. Therefore, surgical treatment by single-tooth osteotomy (STO) and corticotomy for the anterior ankylosed tooth were considered and performed using a CAD/CAM surgical guide, based on presurgical computer-based simulation surgery. Orthodontic and orthopedic treatments were completed at 10 months after surgery. The patient showed a favorable course of healing, with no mobility issues or gingival recession 3 years after single-tooth osteotomy and corticotomy surgeries. A favorable outcome was finally achieved by applying orthopedic treatment combined with STO and corticotomy for the anterior ankylosed tooth. Orthodontic treatment with minimally surgical method is recommended in an adolescent patient with skeletal Class III malocclusion and anterior open bite

    Endoplasmic Reticulum Stress in the β-Cell Pathogenesis of Type 2 Diabetes

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    Type 2 diabetes is a complex metabolic disorder characterized by high blood glucose in the context of insulin resistance and relative insulin deficiency by β-cell failure. Even if the mechanisms underlying the pathogenesis of β-cell failure are still under investigation, recent increasing genetic, experimental, and clinical evidence indicate that hyperactivation of the unfolded protein response (UPR) to counteract metabolic stresses is closely related to β-cell dysfunction and apoptosis. Signaling pathways of the UPR are “a double-edged sword” that can promote adaptation or apoptosis depending on the nature of the ER stress condition. In this paper, we summarized our current understanding of the mechanisms and components related to ER stress in the β-cell pathogenesis of type 2 diabetes
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