APT System Research Articles

Analysis of Coaxiality Error Induced by the Cube Corner Retro-Reflector Geometrical and Assembly Errors of an Acquisition, Pointing, and Tracking System

Satellite laser communication is a promising technology for the next-generation communication system. Its communication performance is subject to the APT beam-pointing accuracy. One of the most important problems is reducing the coaxiality error before the APT starts working. However, the coaxiality error is difficult to correct effectively owing to the lack of empirical guidance based on qualitative analysis. We study the inducement that will generate coaxiality errors. The mathematical model of the influence of the CCR dihedral angle error and planeness error on the spot centroid measurement are built, and an analysis is performed. The model of the beam-pointing error induced by the APT element’s assembly error is built, and the pointing error change rule is explored. Furthermore, the coaxiality performance simulation is performed in the presence of a CCR geometrical error while considering the assembly error. The results show that the coaxiality error has a nonlinear characteristic. The CCR planeness error has a greater influence on coaxiality deviation than that of dihedral angle error under certain conditions. This research is relevant to the design and test work of the APT system.

A Comprehensive Update on Nanotechnology in Functional Food Developments: Recent Updates, Challenges, and Future Perspectives.

The food business makes extensive use of lipophilic bioactive substances derived from plants, such as phytosterols, antimicrobials, antioxidants, ω3 fatty acids, tastes, and countless other constituennts. The preponderance of these bioactive substances, nevertheless, is just about unsolvable in hydric solution and unbalanced at a particular eco-friendly provocation, such as sunlight, temperature, and oxygen, in construction, transference, storage, and employment, for example, icy, chilling, desiccation, warm air dealing out, or machine-driven agitation. According to this standpoint, there are high-tech hitches that must be resolved to inform functionality for the social figure due to the lipophilic bioactive dearth of solubilization, bioavailability, and permanency. This leads to failure in commercialization and quality enhancement. Nanotechnology can generally be used to manufacture nano-kinds of stuff like nano-emulsion, nanoparticles, nanostructured materials, and nanocomposites. The creation of functional foods has attracted a huge interest as our consideration of their affiliation with nourishment and human health has grown. There are still a number of problems that need to be fixed, such as finding useful substances, figuring out ideal intake amounts, and fashioning apt food conveyance systems in addition to product compositions. In several of these areas, new methods and materials developed through nanotechnology have the potential to offer fresh explanations. The present article provides a thorough examination of nanotechnologies employed in the development of functional foods. It outlines the current patterns and forthcoming outlooks of sophisticated nanomaterials in the food industry, with particular emphasis on their applications in processing, packaging, safety, and preservation. The utilization of nanotechnologies in the food industry can improve the "bioavailability, taste, texture, and consistency of food products". This is accomplished by manipulating the particle size, potential cluster formation, and surface charge of food nanomaterials. Furthermore, this paper examines the utilization of nano-delivery systems for administering nutraceuticals, the cooperative effects of nanomaterials in safeguarding food, and the implementation of nano-sensors in intelligent food packaging to monitor the quality of stored food. Additionally, the customary techniques employed for evaluating the influence of nanomaterials on biological systems are also addressed. This review gives a general synopsis of the newfangled possibilities and hitches for systems built on nanotechnology for the creation of functional foods in the future.

Design and Simulation Analysis of Piezoelectric Ceramic Tube-Based Fiber Optic Nutator Applied to an Intersatellite Laser Communication System

The signal-receiving end of acquisition, pointing, and tracking (APT) systems applied to intersatellite laser communication terminals usually uses a fast-steering mirror (FSM) to control the fiber-coupling process, has a complex structural design, and induces large errors in the nonideal coaxial optical path. Herein, we propose a fiber-optic nutator using a piezoelectric ceramic tube (PCT) as the driving unit that allows scanning in the focal plane of the light signal to achieve active fiber coupling in the APT system. Specifically, this article describes the structural design principle of a PCT-based fiber optic nutator, establishes a simulation model of the mechanism, and proves the correctness of the simulation model by measuring the deflection angle of a PCT based on a parallel light collimator. The minimum accuracy of the designed nutator was 0.145 μm, the maximum nutation radius R was 20.09 μm, and the maximum nutation bandwidth was 20 kHz, as determined through simulation. Finally, the design parameters of the nutator were evaluated. The PCT-based fiber optic nutator, which met the design parameters, structurally replaced the fiber optic coupling component FSM and fine tracking camera in conventional APT systems successfully. Therefore, the PCT-based fiber optic nutator allows the active coupling control of signal light to a single-mode fiber (SMF) based on energy feedback on a theoretical basis and promotes the lightweight design of relay optical paths in APT systems. In addition, with future work in optimization of the nutation control algorithm, the scanning range and accuracy of the nutator can be improved.

Destructive testing on mitotic machinery: Probing the mechanics of fission yeast cell division by laser ablation.

When eukaryotic cells divide, the mitotic spindle has the critical task of segregating chromosomes, ensuring that each new daughter cell receives exactly one copy of its genetic information. To do so, it must self-assemble and then generate force to pull chromosomes to the right place at the right time. While decades of work has produced a detailed census of many of the molecules required for cell division, considerable gaps remain in our understanding of the mechanics of mitosis. How is force exerted in the correct locations at the correct times? How does force propagate between structures with different material properties, and how are those properties themselves tuned for different functions? How can complex cellular machinery self-assemble without a “director” telling all the parts where to go? Due to its structurally simple mitotic spindle, which consists of a single bundle of around a dozen microtubules, the fission yeast S. pombe is a particularly apt system for probing biophysical mechanism. Importantly, S. pombe undergoes closed cell division, which means its spindle assembles within the nuclear envelope. Considerable changes in envelope shape accompany spindle elongation and chromosome segregation, but the mechanical interactions between the nuclear envelope and the mitotic spindle are poorly understood. I will present work combining live cell confocal imaging, laser ablation, quantitative analysis, and molecular perturbations to examine how the fission yeast cytoskeleton accomplishes the mechanical functions required for cell division, and how it coordinates with the nuclear envelope. I will also discuss how laser ablation reveals mechanical differences between the S. pombe spindle and that of its sister species, S. japonicus, which undergoes semi-open mitosis. These differences suggest how features of spindle organization may evolve to match their mechanical constraints.

The Role of Transient Intermediate Structures in the Unfolding of the Trp-Cage Fast-Folding Protein: Generating Ensembles from Time-Resolved X-ray Solution Scattering with Genetic Algorithms.

The Trp-cage miniprotein is one of the smallest systems to exhibit a stable secondary structure and fast-folding dynamics, serving as an apt model system to study transient intermediates with both experimental and computational analyses. Previous spectroscopic characterizations that have been done on Trp-cage have inferred a single stable intermediate on a pathway from folded to unfolded basins. We aim to bridge the understanding of Trp-cage structural folding dynamics on microsecond-time scales, by utilizing time-resolved X-ray solution scattering to probe the temperature-induced unfolding pathway. Our results indicate the formation of a conformationally extended intermediate on the time scale of 1 μs, which undergoes complete unfolding within 5 μs. We further investigated the atomistic structural details of the unfolding pathway using a genetic algorithm to generate ensemble model fits to the scattering profiles. This analysis paves the way for direct benchmarking of theoretical models of protein folding ensembles produced with molecular dynamics simulations.

Design, development and model analysis of lower extremity Exo-skeleton.

Over the past few years the growth and development of exo-skeleton has dramatically raised with the development of precise control elements and actuation systems. Many exo-skeleton systems have been designed, developed and tested for performance optimization. In the recent years, the significance of exo-skeleton in medical fields have got increased and are used in providing therapy and rehabilitation to the patients. With this development there comes the importance for analysis and control of the exo-skeleton for precise functioning and to avoid malfunction of the system in the later part. Dynamic analysis of limb joints is essential to better facilitate a deeper understanding of the exo-skeleton limb during various environmental conditions like varied loading. The dynamic model so developed will assist in choosing an apt actuation system based on the torque requirement of the model.This paper focusses on the analysis of a 2DOF lower limb active control exo-skeleton system and makes a torque calculation for actuator selection for the lower limb to provide rehabilitation to the patients as wearable walking aid. The work also makes a trajectory planning for the lower limb to move in sequence for making a walking cycle with angular limitations to avoid damage to the user's limbs. The motion analysis for the developed lower limb Exoskeleton as per the analysis is 52.055 Nm at hip joint 11.677 Nm at knee joint.

Economic method, public policy, and society: Adolph Lowe’s political economics

Adolph Lowe questioned the mainstream approach to economic theory beginning in the mid-1920s and spanning a 60-year career. Lowe developed a tripartite approach to political economics which consists of (1) redefining the economic method, (2) structural modelling and analysis, (3) and redefining the political and educational philosophy. This article details Lowe’s basis for economic and public policy and pays particular attention to the need to create an apt political system centred on fostering economic democracy and promoting the interests of the public as a collective towards social ends.

EXAMINATION OF THE ADEQUACY OF RESOURCES PREPAREDNESS FOR IMPLEMENTATION OF INTEGRATION OF DIGITAL LEARNING IN PUBLIC PRIMARY SCHOOLS IN MERU COUNTY, KENYA

Purpose: Digital learning integration (DLI) in schools has positive implications for the education systems. DLI programme was rolled out in Meru County alongside other 46 counties in Kenya in 2016 after several postponements. However, DLI programme adoption is attributed to preparation challenges. This study examined the adequacy of resources on implementation of DLI programme in public primary schools in Meru County.
 Methodology: The study was guided by Roger’s diffusion of innovation theory and Boum’s project management cycle. The study used descriptive survey design and adopted mixed method approach. The study targeted 710 public primary schools in 9 sub-counties. Data was provided by 710 head teachers, 7032 teachers, 2004 Parent Teachers Association (PTA) executive members, and 25,720 grade 3 DLI programme pioneer pupils. A 10% sample of schools was considered sufficient which was obtained using simple random sampling technique. As a result, 71 head teachers and 703 teachers were obtained. Purposive judgmental sampling technique was used to get 201 PTA members. Further, Sloven’s formula was used to get a sample size of 396 pupils that formed Focus Group Discussion (FGD) each consisting of 8 learners, and 9 SCDEs were purposively sampled. Questionnaires were used to collect data from head teachers, teachers and PTA while interview schedules and FGDs were used to get data from SCDEs and from learners respectively. Observational schedule was also used to provide guide for focusing observation and recording data. The research tools were pre-tested for validity and reliability. The quantitative data was analyzed using IBM SPSS Statistics for Windows version 22. The data was analyzed, interpreted and reported using percentages, measures of central tendency. Univariate regression analysis was used to test hypothesis. Qualitative data was analyzed according to themes based on study objective and reported in narratives.
 Findings: Through computation of Pearson product moment correlation coefficients confirmed that there is significant positive correlation (r = 0.825) between variable adequacy of digital learning resources against DLI at 0.05 level of significance. Resources such as tablets, internet connectivity, computer laboratory and electricity were noted to be inadequate. Learners who were introduced to DLI appreciated and were always eager to learn using the available digital technology resources. In addition, there was no monitoring or evaluation of the digital programme after roll out by quality assurance and standards officers as per the policy guidelines. The study concluded that preparations for digital programme were inadequate. The findings will be useful to educationists, parents, teachers, and policy makers.
 Unique contribution to theory, practice and policy: The study recommended that MoE should go back to the drawing board and come up with proactive measures on provision of digital learning resources. Adequate resources such as tablets, desks, computer laboratories, network connectivity and electricity among others should be availed to all schools. Tablets available are too few to be distributed to pupils during this period of COVID-19 pandemic leading to resource wastage. MoE should own the innovation and facilitate its full adoption by coming up with apt monitoring and control systems. Political objectives should not be allowed to overshadow policy structures such as planning, management and administrative processes.

A multi-clause dynamic deduction algorithm based on standard contradiction separation rule

In the past decades, automated theorem proving (ATP) for first-order logic has made good progress, in which binary resolution inference rule plays a crucial role. However, as shown in the latest benchmark library of the ATP system, there are still many practical problems that have not been resolved or cannot be effectively resolved. Recently, in order to overcome the limitations of ATP based on binary resolution inference rules, a novel multi-clause dynamic standard contradiction separation (S-CS) inference rule and its automated deduction theory have been proposed. Based on this theory, this paper first clarifies the generality of this S-CS rule by comparing it with some well-known variants of the binary resolution rule, and then focuses on how to design a specific and effective algorithm along with search strategies to realize the S-CS based deductive theory with its implementation. Specifically, the present work proposes a novel S-CS dynamic deduction algorithm (in short SDDA) based on different strategies and summarizes its implementation procedures. In addition, we focus on evaluating whether SDDA, as a novel perspective multi-clause dynamic automatic deduction algorithm, can be applied on top of the current leading ATP system architectures to further improve their performances. Therefore, SDDA is applied to the current leading first-order ATP systems, i.e., Vampire and E, respectively forming two integrated APT systems, denoted as SDDA_V and SDDA_E. Then the capabilities of SDDA_V and SDDA_E are evaluated on the latest benchmark database TPTP, such as the CASC-J9 problems (FOF division) as well as the hard problems with a rating of 1 in the TPTP benchmark database. The experimental results show the effectiveness of SDDA: SDDA_V outperforms Vampire itself, and SDDA_E, outperforms E itself, and the two improved ATP systems have solved a number of hard problems with the rating of 1 in TPTP, that is, some problems in the latest benchmark database TPTP which have not yet been solved by other current first-order ATP systems.

Machine-vision-based acquisition, pointing, and tracking system for underwater wireless optical communications

Due to the proliferation of underwater vehicles and sensors, underwater wireless optical communication (UWOC) is a key enabler for ocean exploration with a strong reliance on short-range bandwidth-intensive communications. A stable optical link is of primary importance for UWOC. A compact, low-power, and low-cost acquisition, pointing, and tracking (APT) system is proposed and experimentally demonstrated to realign the optical link within 0.04 s, even when the UWOC transmitter and receiver are in relative motion. The system successfully achieves rapid auto-alignment through a 4 m tap water channel with a relatively large number of bubbles. Furthermore, the required minimum illumination value is measured to be as low as 7.1 lx, implying that the proposed APT scheme is robust to dim underwater environments. Meanwhile, mobility experiments are performed to verify the performance of the APT system. The proposed system can rapidly and automatically align moving targets in complex and unstable underwater environments, which can potentially boost the practical applications of UWOC.

The application of ultramicroscope with high precision in light and small laser communication system for micro-nano satellite

With the rapid development of space laser communication technology, it is possible to realize mass data transmission between satellites in low orbit. Micro-nano satellite is the first choice of low orbit communication satellite because of its lightweight, small size and low cost. Laser scanning technology is a kind of technology that can accurately control the direction of laser beam. It has been widely used in the field of space laser communication. In this paper, after analyzing the technical requirements of the scanning mirror with APT system for microsatellite, a kind of miniature scanning mirror is selected to realize the accurate pointing of the beam.

Efficient pothole detection using smartphone sensors

Road safety remains a casualty in India, with potholes wrecking asphalt pavements by the dozens. A study in 2017 recorded that potholes caused the budget for road safety to increase by a whopping 100.4 per cent, and even doubled the death toll from that of the year prior. To address this situation, an effective solution is required that ensures the drivers’ safety and can prove beneficial for long term measures. This can be established by employing an apt pothole detection system which is simple yet functional. In this paper, the method for such a system is described which uses accelerometer and gyroscope, both built in the modern day smartphones, to sense potholes. Pothole induced vibrations can be measured on the axis reading, making them distinguishable. Our proposed Neural Network model is trained and evaluated on the data acquired from the sensors and classifies the potholes from the non-potholes. The neural network gives a classification accuracy of 94.78 per cent. It also presents a solid precision-recall trade-off with 0.71 precision and 0.81 recall, considerably high for a problem with class imbalance. The results indicate that the method is suitable for creating an accurate and sensitive supervised model for pothole detection.

Development of Multitarget Acquisition, Pointing, and Tracking System for Airborne Laser Communication

Cluster unmanned aerial vehicles (UAVs) are widely demanded. To achieve high rate and large capacity communication with cluster UAVs, one of the key but still challenge task is to perform multitarget acquisition, pointing, and tracking (APT) under complex airborne environment. To solve this problem, this paper gives one composite axis APT system for multitarget laser communication with cluster UAVs. The APT system consists of a gimbal mirror and piezoelectric fast steering mirrors (FSMs), which can achieve independent and synchronous control of multiple optical axes. The cascade control scheme is designed for the gimbal mirror and the H∞ controller is designed for the FSM. To further improve the control accuracy, the hysteresis compensator based on least square support vector machines (LS-SVM) is proposed. The pruning error minimization method of LS-SVM is applied to reduce the computational cost. The simulation studies validate the control performance of the multitarget APT system. Finally, the experimental prototype is developed. The experimental results further validate the effectiveness of the proposed multitarget APT system.

Research on APT Spot Detection Algorithm in Space Optical Communication

In space laser communication system, the coarse tracking accuracy of the APT system directly affects the field of view selection and accuracy of fine tracking system, and the accuracy of the selection of the spot center position directly affects the accuracy of the coarse tracking system. Therefore, the selection of reasonable spot detection algorithm is an important guarantee for the stable establishment of APT system. Centroid method, hough transform method, and circle fitting method are often used in the analysis of spot center and the realization of spot tracking. In order to improve the detection accuracy and anti-jamming performance, this paper compares and analyzes several commonly used spot detection methods, and obtains the applicable conditions of each algorithm.

Usability Testing of “CHIsel”: Cultural Heritage Information System Extended Layers of Interactive 3D Computer Generated Images and Relational Database

CHISel is a cultural heritage information system that supports the extensive organization, tracking, and implementation of data on 3D computer generated models of archaeological artefacts and site. We conducted a detailed user test of CHISel, to assess the usability of the complex and numerous system features, in order to assess the efficiency, user satisfaction, memorability, learnability, and accuracy. These qualities are particularly crucial to software like CHISel, which has a high learning curve for new and inexperienced users, involves professional, field-specific users, requires high-precision, high accuracy and contains a large amount of complex system features that must function well in order for the program to work as an apt integrative system.

A novel initial temperature-based methodology to predict the optimal thickness in microwave thin layer drying process

Abstract Compared with traditional hot air drying method, the existence of optimal material layer thickness is a significant phenomenon in microwave thin layer drying process. In the current work, a new initial temperature-based methodology is proposed to predict the optimal thickness and to evaluate the effect of influential factors on optimal thickness. The evaluated optimal material layer thickness by the proposed methodology is consistent with experimentally measured value, and hence confirms that the optimal layer thickness can be predicted exactly through the average temperature of bulk material at the initial 1st min during pre-heating stage. With the help of the proposed methodology, it is discovered that attenuation factor, β, surface convective heat transfer coefficient, h, and environmental air temperature, T e are the main factors that affect the optimal thickness. And a larger β or T e tends to result in a smaller optimal thickness, while the situation for h is just the opposite. These results can play a crucial role in designing apt continuous microwave tunnel drying system or aid in guiding their operations.

Yankee Ingenuity in Theories of American Economic Development, from the Founding to the Closing of the Frontier

Since its founding, especially before the late nineteenth-century closing of its frontier, the United States has been a laboratory for the creation and application of theories of economic development. A salient tradition in American economic thought has held, first, that Americans are characterized by their ingenuity; second, that a nation of such people, with such abundant land and separated from the institutions and antagonisms of Europe, needs a different system of economic ideas for understanding its development prospects; third, that any apt system of ideas must spotlight the role of ideas in development. Economic thinkers including Alexander Hamilton, Henry Charles Carey, and Henry George shared these notions, although to varying degrees and with various implications. When economists of the present day turn to history to understand the role of invention and adaptation in economic development, they invite our getting reacquainted with that tradition.

Effects of optical dopants and laser wavelength on atom probe tomography analyses of borosilicate glasses

AbstractAtom probe tomography (APT) is a novel analytical microscopy method that provides three dimensional elemental mapping with sub‐nanometer spatial resolution and has only recently been applied to insulating glass and ceramic samples. In this paper, we have studied the influence of the optical absorption in glass samples on APT characterization by introducing different transition metal optical dopants to a model borosilicate nuclear waste glass. A systematic comparison is presented of the glass optical properties and the resulting APT data quality in terms of compositional accuracy and the mass spectra quality for two APT systems: one with a green laser (532 nm, LEAP 3000X HR) and one with a UV laser (355 nm, LEAP 4000X HR). These data were also compared to the study of a more complex borosilicate glass (SON68). The results show that the analysis data quality, particularly the compositional accuracy and sample yield, was clearly linked to optical absorption when using a green laser, while for the UV laser optical doping aided in improving data yield but did not have a significant effect on compositional accuracy. Comparisons of data between the LEAP systems suggest that the smaller laser spot size of the LEAP 4000X HR played a more critical role for optimum performance than the optical dopants themselves. The smaller spot size resulted in more accurate composition measurements due to a reduced background level independent of the material's optical properties.

Autonomous shooting at middle size space debris objects from space-based APT laser systems

This paper is motivated by the need of removing middle size space debris objects. It deals with the problem of increasing the pointing accuracy while shooting at these objects by means of autonomous space-based APT systems endowed with very narrow laser beams. It is shown that shooting at these objects with these systems is the one single ballistic problem that becomes singular in space. This means that the shooting direction that is to be implemented by any of these systems to reach an object at a given instant can only be hopefully implemented after the object has been previously reached. Thus, the problem becomes backwards recurrent with no end for any object–system configuration, except when the LOS direction remains constant for some period of time. It is also shown that the implementation of the point-ahead angles from the data acquired prior to the respective shootings is essential to keep accuracy. In fact, one single omission during the action may cause errors larger than the size of the objects. As a consequence, we find that there is only one way for an autonomous system to minimize the pointing errors: any shooting sequence to any of these objects must be started when the transverse component of the relative velocity of the object with respect to the system is zero (actually, as close to zero as possible).

Intracellular delivery of recombinant proteins via gold nanoparticle–DNA aptamer composites is independent of the protein physicochemical properties and cell type

Abstract Here, we report that the gold nanoparticle–DNA aptamer (AuNP–Apt) conjugate-based system can efficiently deliver recombinant proteins into mammalian cells in a manner independent of their size, isoelectric point, and cellular localization. Additionally, AuNP–Apt system-assisted protein delivery can be effective on primary and stem cells, indicating that its use is not limited to fast-dividing cells. We further show that the intravenously administered AuNP–Apt system can deliver proteins into rat organs. Our findings show that this system can serve as a simple, efficient, and versatile platform for the delivery of recombinant proteins into mammalian living systems.