PurposeThis study explores the development trajectory of private tutoring in Bangladesh. Specifically, it illustrates how private tutoring has emerged and expanded in the country's education system and examines how governments have responded on this issue.Design/methodology/approachThe authors adopted a case study methodology for this study. Data were gathered from different secondary sources such as books, official documents, scholarly articles, and newspaper reports. The data analysis process consists of three-phases of activities: data reduction, data display, and conclusion drawing/verification.FindingsPrivate tutoring historically existed in Bangladesh. It is rapidly expanded in the country's education system – from primary to higher secondary level. Currently, it has reached an industrialization stage, where commercial coaching has become a major type of tutoring. The expansion of private tutoring is the inevitable result of the continued privatization and marketization of education. To bring the private tutoring under a framework, the government has taken some regulatory measures that can be characterized as “laissez-faire.” The existing measures are largely ineffective, as the policy makers followed an “top-down” approach when framing the policies.Originality/valueThis study, to the best of the authors' knowledge, is the first to target the historical aspects of private tutoring in Bangladesh. It has potential to fill out the literature gap on private tutoring by analyzing its policy aspect.
Robot-assisted therapy has gained wide attention in rehabilitation engineering, allowing patients with lower limb motor disorders to perform repeatable and consistent upright bipedal walking. The goal of this paper is to develop a novel wearable powered exoskeleton that enables the paraplegic to perform basic daily movements for active rehabilitation training of lower limbs. Mechanical structure and driving devices of the exoskeleton are reasonably designed and selected to ensure natural interaction with the user and provide sufficient driving torques in the course of walking. In order to avoid unwanted interaction forces between the exoskeleton and the patient, the passive exoskeleton testing system is proposed to measure and record various postures as the reference trajectories. In addition, a cascaded proportional–integral–derivative controller is designed to complete walking assistance tasks in passive control modes. Four typical trajectory tracking tasks are carried out for the sake of evaluating the accuracy and effectiveness of the proposed control strategy. Further experiments were conducted by a healthy subject wearing the rehabilitation exoskeleton to perform sit-to-stand and level walking, and the results demonstrated that the developed robot-assisted system had the natural period and favorable response patterns.
This paper focuses on the carrier estimation performance improvement in Mars entry, descent, and landing (EDL) flights. Carrier reconstruction could be used for trajectory derivation and Martian atmosphere profile inversion, and is the critical information for mission operations, as it helps determine the flight status of the spacecraft, demodulate the downlink information. The current approach is maximum likelihood estimation based on a two-dimensional (2D) maximum energy search algorithm, which computes the grid energy over all the combinations of frequency cells and frequency rate cells among the search space. Although it has good performance on robust estimation, the frequency estimation accuracy is limited due to the short coherent integration. An instantaneous frequency rate tracking approach based on the cubic phase function (CPF) is proposed that directly estimates the instantaneous frequency rate over the frequency rate cells, followed by the frequency estimation among the frequency cells. A sequential estimation method is introduced to propose the sequential CPF statistics, which uses the a priori Doppler phase information to suppress the noise squaring loss inherent in the standard CPF statistics. Simulations have been made on the released Mars Science Laboratory EDL trajectory for the two approaches, which show that considerable estimation improvement has been achieved for aerobraking flight by the new algorithm.
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