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The current U.S. extravehicular activity (EVA) suit is pressurized at 0.29 atm, which creates a risk of decompression sickness (DCS). If higher mobility is acquired, higher inner pressure is allowed. We previously demonstrated a wider range of motion (ROM) with lower muscle force using an elastic glove pressurized at 0.65 atm compared with a nonelastic glove pressurized at 0.29 atm, which simulated the current U.S. EVA suit. Pressurization at 0.65 atm is the lowest pressure that avoids DCS without prebreathing. For larger joints, other restraint parts are needed to depress ballooning of the elastic material during pressurization. In the present study, we developed hard restraint parts for the knee joint covering the elastic garment for the lower limb, and compared the ROM and flexion force between a dual and single axis during pressurization at 0.65 atm. The joint motion and force required during flexing action were recorded. During flexion, the ROM was significantly larger and the peak force was significantly lower with the dual-than single-axis part. Thus, a dual axis of hard restraint part has higher mobility than a single axis during pressurization without a risk of DCS.

We and others recently developed rapid tilt-series acquisition methods for cryo-electron tomography on a Titan Krios G3i equipped with a single axis holder and a K-series direct electron detector and showed that one of these, the fast-incremental single exposure (FISE) method, significantly accelerates tilt-series acquisition when compared to traditional methods while preserving the quality of the images. Here, we characterize the behavior of our single axis holder in detail during a FISE experiment to optimally balance data quality with speed. We explain our methodology in detail so others can characterize their own stages, and conclude with recommendations for projects with different resolution goals.

Roundabouts became popular worldwide as a tool to reduce the number of car accidents and the EU encourages and promotes this technology as a solution to the problems of urban and extra-urban traffic. RAST (Roundabout Solar Tracking) systems are designed to exploit the available space in roundabouts, which are already equipped and monitored, in order to produce electricity with a photovoltaic single axis tracking system. The energy produced can be used directly by the surrounding facilities or stored and consumed later or channelled to nearby car charge points. The amount of energy that can be produced on a single roundabout is limited by the land size and is normally in the range 100-400 kWp, but the number of suitable roundabouts in cities is high. Therefore, RAST could make an important contribution to the energy production.

A practical inertial-measurement-unit-based method is proposed to measure the angle of a single-axis rotation, where the axis rotation is invisible or inaccessible. The proposed method utilises the angular velocities of an inertial-measurement unit (IMU) to compute the orientation of the rotating axis. An equation with respect to the unknown rotation angle is first developed due to that the attitude angles of IMU vary as the measured target rotates. An interpolation algorithm is proposed to solve the equation, and simulations are performed. Finally, with a turntable and an IMU, comparative experiments are conducted to validate the proposed method. Results demonstrate the robustness to initial noise and the effectiveness under different situations.The proposed method is practical because of its simple structure, flexible installation and applicability in complex environments. Another more contributions of this study are a feasible approach to measure the orientation of the rotating axis. This method solves the problem of complex and difficult installation of angle measuring equipment in specific environments. It is simple and suited for use in the real-time calculation of angular displacement. It can be used to measure the rotation angle of rotating motors or the rotating axis of some equipment.

Varity of applications in science and engineering require technical abilities to conduct force measurements with high accuracy and precision in traceable manner. An example of such is the Lorentz Force Velocimetry (LFV), where forces of about 1 μN and below acting in horizontal direction on the object with approximately 1 kg weight are required to be resolved. In this paper we present a setup initially developed for this application, however, showing also a potential to be used elsewhere as a portable and conceptually unique setup. By the setup presented the force measurements in horizontal direction with 20 nN are resolved with 5 % to 7 % accuracy on the full range of the scale up to several mN.

In France, sweet cherry is generally trained in the now well-known vase training system. Growers know how to form and to prune trees in this system in order to have a good balance between yield and size of fruit. But in order to reduce production costs and to protect cherry fruit, other training systems that could be pruned mechanically and that allow installation of covers to protect against damage from rain or insects are being studied. A trial was planted in 2005 in order to compare agronomic and economic performances of three training systems using the scion cultivar 'Folfer(cov)': vase, single axis, and fruiting wall. Two rootstocks, Maxma® 14 and Tabel® Edabriz, were studied for the vase and fruiting wall systems, but only Tabel® Edabriz was used for the single axis. The cost to install the fruiting wall and single-axe systems is higher than the vase. However, the fruiting wall with Tabel® Edabriz exhibits greater precocity than the other training system/rootstock combinations. Fruiting wall with Tabel® Edabriz produces greater yields ha-1 with equal fruit quality. By contrast, sweet cherry on Maxma® 14 trained to the fruiting wall enters production later, and with lower yields than all other training system/rootstock combinations in this trial, such that after 8 years the cost of the plantation establishment had not yet been compensated with the production. Research findings regarding training system/rootstock combinations, yield, and fruit quality should be confirmed. Further, the question of long term performance must be studied.

That solar tracking improves energy yields from solar harvest systems is not debatable. Nor is the under powering of tropical Africa amidst plenty of energy resources – including solar. This paper presents a review of recent literature on tracking as applied to domestic solar harnessing devices. The purpose is to find basic requirements in design of a suitable solar tracker for the region’s rural homes. It is concluded that Single axis passive trackers possibly will stand better chances of acceptability in the region.

Incremental forming (IF), a novel sheet material forming technique which has the ability to eliminate the need for die sets, forms sheet material through the use of a non-cutting tool that gradually deforms the sheet material into the desired shape. Generally, the shape of the tool tip is a hemisphere. In the following works, the authors validate a novel tool shape, presented in Part 1 of this research, that allows forming of the sheet material in multiple directions at a rapid rate. The works described herein demonstrate that a more complex tool tip can result in greater formability, improved surface finish, and reduced springback. The tested tool tip shape described herein is that of two hemispherical tips, revolved about a common radius from a single axis, vertically offset to half of the tool path's step size.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Accelerated life testing has major impact on the success of a ground vehicle development program. Accelerated life testing profile should represent the customer usage so that optimum design can be achieved. A novel approach incorporating finite element analysis and vehicle durability test data into single axis accelerated life test profile generation was developed in this study. The proposed approach was successfully applied to the engine mount bracket of a heavy duty truck engine and it is validated by vehicle and rig tests. The accelerated life testing procedure developed in this study is applicable to many components of ground vehicles. It is possible to test components at high confidence level and low cost with this approach.

Chang [1] proposed a method to determine the gain of a tracked panel, rotated about a horizontal east-west axis with continuous adjustment to minimize the angle of incidence, according to three kinds of radiation sources will be considered, i.e. the extraterrestrial radiation, global radiation predicted by empirical models under clear sky situation and global radiation observed in Taichung (φ = 24.2° N), Taiwan. In this article, Chang [1] incorrectly calculated the daily variation of the solar azimuth angle. The mentioned error could have its influence on all other results. The present comments are focused on correcting the calculated solar azimuth angle by Chang [1] and to discuss the sensitivity of other calculated values to this observed error.

In consideration of the stress concentration, unified compliance equations for conventional single-axis hinges are presented. The relationship between the stress concentration and the compliance of corner-filleted flexure hinges is first analyzed. Considering the stress concentration, coupled with a wide range of geometrical parameters, empirical compliance equations for conventional flexure hinges, are then obtained by using the exponential model. Subsequently, the proposed equations are unified. To verify the validity and accuracy of these equations, the characteristics of a bridge-type flexure-based mechanism are then analyzed by the proposed equations and finite element analysis, respectively. The results of compliances and displacement amplification ratios obtained by these two methods are in good agreement. It demonstrates that the empirical compliance equations could be obtained by exponential model, and these equations can be unified.

International audience

With the development of the photovoltaic (PV) technology, more large-scale solar PV plants are integrated to the power grid to relieve the traditional coal-based power plants and reduce the carbon emission. Compared with fixed-tilt (FT) arrays, single-axis tracking (SAT) arrays can produce more power yield. In terms of maintenance fee, SAT arrays are also cheaper than that of dual-axis tracking (DAT) arrays. Thus, SAT systems are becoming a cost-effective option for large-scale PV plant constructions. However, in an Australian PV plant, the power generation of SAT arrays exhibits an unusual phenomenon –– “a valley of power generation” during the midday time. This paper aims to provide an insight about this phenomenon through comprehensive theoretical analysis. Three impact factors, i.e., temperature, tilt angle and incidence angle of direct irradiance to the panel are investigated which determine the power generation characteristics of SAT arrays. The findings of this study can provide valuable insights for PV owners/utilities to better understand the SAT operational behaviors and manage the demand response.

In single-axis rotation inertial navigation system, shaft orientation error will lead to the step effect of the ship attitude result. We derived the mathematical relationship between the shaft orientation error and the ship attitude measurement error, and proposed an online shaft orientation calibration method based on the mathematical relationship. The output data of the shaft angle-encoder and the inertial measurement unit (IMU) was adopted to calculate the ship attitude, and then the real shaft orientation was calculated inversely according to the measured ship attitude error. Experimental results showed that this method can calibrate the shaft orientation in a high accuracy.

The emergence of cost-competitive bifacial PV modules has raised the question of the additional value of bifacial 1-axis tracking arrays, in particular when considering rear-irradiance losses from the tracker system itself. In this work, the effect of different geometries and materials of torque tubes is evaluated through ray-trace simulations and found to cause rear irradiance shading factors between 2% to 8% for systems without gap between the modules in 2-UP configuration. Inclusion of a gap between the modules can offset the shading factor. Electrical mismatch is also evaluated for the various configurations, and a methodology to apply shading factor and electrical mismatch loss to rear irradiance from the calculated loss in DC power, which averages 1% for the systems explored here, is proposed.

Variation in resource acquisition strategies enables plants to adapt to different environments and may partly determine their responses to climate change. However, little is known about how belowground plant traits vary across climate and soil gradients. Focusing on interior Douglas-fir (Pseudotsuga menziesii var. glauca) in western Canada, we tested whether fine-root traits relate to the environment at the intraspecific level. We quantified the variation in commonly measured functional root traits (morphological, chemical, and architectural traits) among the first three fine-root orders (i.e., absorptive fine roots) and across biogeographic gradients in climate and soil factors. Moderate but consistent trait-environment linkages occurred across populations of Douglas-fir, despite high levels of within-site variation. Shifts in morphological traits across regions were decoupled from those in chemical traits. Fine roots in colder/drier climates were characterized by a lower tissue density, higher specific area, larger diameter, and lower carbon-to-nitrogen ratio than those in warmer/wetter climates. Our results showed that Douglas-fir fine roots do not rely on adjustments in architectural traits to adapt rooting strategies in different environments. Intraspecific fine-root adjustments at the regional scale do not fit along a single axis of root economic strategy and are concordant with an increase in root acquisitive potential in colder/drier environments.

A 25-MW solar power plant was commissioned in Andhra Pradesh, India in the first quarter of 2016. The 3 MW of single-axis tracker arrays co-located with 22 MW of fixed-tilt arrays provide a direct comparison of their performance under variable irradiance and thermal conditions to inform the cost-benefit analysis of future installations. Through March 2019, the single-axis tracker arrays have delivered an increase in energy yield of more than 14%.

It is very important to be able to calculate the optimum land usage of PV systems. If PV system is poorly designed, it would result in either a waste of land due to too large an area, or the loss of power generation because of shading between arrays. Optimum land usage of PV plants can make efficient use of land and maximize the power generation of PV by avoiding shading, so that the PV project can get maximize benefits. PV array has various types, fixed arrays, single axis tracking and double axis tracking. The geometry method of calculating the land usage of PV systems is provided in this paper. The contents of this paper has been published in IEC TR 63149-2018 [1].

This work consists of design and experimental validation of Pulse Width Modulation (PWM) scheme for a cold gas thruster system which is driven by on/off type of actuators. PWM scheme designed according to the characteristics of the on/off type of actuators obtained by the developed solenoid valve model and the experimentation. Angular position of the single axis rotational platform is controlled by the PWM scheme and the state feedback angular position controller. The PWM scheme and the angular position controller are experimentally tested and the results are presented in this paper.

This paper discusses “supersoft” control of final parameters in a single-axis gyrostabilizer, providing the required precision and “softness” of the gyro-stabilized platform (GSP) rotation from arbitrary initial position to the preset final state. The problems of the synthesis of “supersoft” terminal regulators for GSP and gyro unit (GU) are presented. The mathematical simulation of “supersoft” control is carried out. The conclusions on application of “supersoft” control of final parameters in a single-axis gyrostabilizer are drawn.

Aiming at the attitude estimation errors existed in the attitude measurement system using the magnetic, angular rate and gravity (MARG) sensors, a novel attitude compensation algorithm based on the neural network using data from sensor networks is proposed in this paper. It provides a more accurate measurement with simple implementation. A simple Kalman filter (KF) is designed to achieve prior attitude estimation. A back-propagation neural network is designed to compensate the attitude errors for the KF. The neural network is trained by the data from MARG sensor networks and errors of attitude estimation algorithm. Taking the data from triaxial MARG sensors as inputs, the trained network could predict the estimated attitude errors in Euler-angles form. Moreover, to validate the effectiveness of the proposed algorithm, two different experiments are accomplished. In the first experiment, the designed neural network is utilized to compensate the attitude estimation errors of a micro quadrotor helicopter using the publicly available datasets. In the second experiment, the KF is combined with the neural network to estimate the attitude of a self-designed single axis platform. Results show that the estimated attitude is closer to actual attitude after compensation which indicates that it is effective to utilize the neural network to compensate for estimation errors in attitude detection field even the attitude estimation algorithm is a simple Kalman filter.

Purpose. Surgical lights in the operating rooms are typically installed in a single axis in the center of the room or in two axes on both sides of the operating table. In the single-axis installation, the air-conditioning outlet cannot be placed in the center of the ceiling, which may affect the air current. Therefore, we measured the air current and cleanliness in two equivalent operating rooms using a vertical laminar airflow system equipped with either single-axis or double-axis surgical lights. Methods. Air current was measured using a three-dimensional ultrasonic anemometer. Cleanliness was evaluated by measuring the amount of dust before and after air-conditioner activation. To visualize the air current, smoke was illuminated on a sheet of laser light while the air-conditioning was stopped, and changes after air-conditioning activation were observed. Results. In the single-axis room, an oblique fast air current flowing from the surrounding air outlet toward the center was observed, and the flow velocity fluctuated greatly. In the double-axis room, uniform downward laminar airflow was observed. The amount of dust at the center decreased significantly faster in the double-axis room; thus, the cleanliness at the center was higher in the double-axis room. Persistent stagnation of smoke was observed below the single-axis lighting, whereas smoke below the double-axis lighting was immediately dispersed and the air cleared even when surgical lights were in the position for surgery. Conclusion. Uniform vertical laminar airflow was formed and high cleanliness was achieved in the center of the room when the surgical lights were arranged in two axes.

Summary: Stroke causes focal brain lesions that disrupt functional connectivity (FC), a measure of activity synchronization, throughout distributed brain networks. It is often assumed that FC disruptions reflect damage to specific cortical regions. However, an alternative explanation is that they reflect the structural disconnection (SDC) of white matter pathways. Here, we compare these explanations using data from 114 stroke patients. Across multiple analyses, we find that SDC measures outperform focal damage measures, including damage to putative critical cortical regions, for explaining FC disruptions associated with stroke. We also identify a core mode of structure-function covariation that links the severity of interhemispheric SDCs to widespread FC disruptions across patients and that correlates with deficits in multiple behavioral domains. We conclude that a lesion’s impact on the structural connectome is what determines its impact on FC and that interhemispheric SDCs may play a particularly important role in mediating FC disruptions after stroke. : Disruptions of brain network function in patients with focal brain lesions are often assumed to reflect damage to critical gray matter regions. Griffis et al. challenge this assumption by showing that network dysfunction primarily reflects the disconnection of white matter pathways, rather than the destruction of gray matter regions. Keywords: stroke, functional connectivity, structural connectivity, functional MRI, diffusion MRI, lesion, structural disconnection, brain networks, resting state, structure-function

We have studied by X-ray diffractometry the crystallographic orientation relationships (CORs) between magnesiochromite (mchr) inclusions and their diamond hosts in gem-quality stones from the mines Udachnaya (Siberian Russia), Damtshaa (Botswana) and Panda (Canada); in total 36 inclusions in 23 diamonds. In nearly half of the cases (n = 17), [111]mchr is parallel within error to [111]diamond, but the angular misorientation for other crystallographic directions is generally significant. This relationship can be described as a case of rotational statistical COR, in which inclusion and host share a single axis (1 df). The remaining mchr–diamond pairs (n = 19) have a random COR (2 df). The presence of a rotational statistical COR indicates that the inclusions have physically interacted with the diamond before their final incorporation. Of all possible physical processes that may have influenced mchr orientation, those driven by surface interactions are not considered likely because of the presence of fluid films around the inclusions. Mechanical interaction between euhedral crystals in a fluid-rich environment is therefore proposed as the most likely mechanism to produce the observed rotational COR. In this scenario, neither a rotational nor a random COR can provide information on the relative timing of growth of mchr and diamond. Some multiple, iso-oriented inclusions within single diamonds, however, indicate that mchr was partially dissolved during diamond growth, suggesting a protogenetic origin of these inclusions.

MIL-HDBK-344A [1] provides a formula for vibration Precipitation Efficiency (PE) and introduces an axis sensitivity factor, but provides inadequate direction to account for multiple axis testing. Per the current direction one can test in all three axes at a chosen level for a duration t, or test for 3t the duration in a single axis and obtain the same PE. This paper provides a consistent means for calculating a comprehensive vibration PE, considering Test Sensitivity that includes the type of vibration screen (simultaneous or sequential axis exposure) and the number of axes included in the screen.

Postural control can be improved with balance training. However, the nature and duration of the training required to enhance posture remains unclear. We studied the effects of 5 min of a self-initiated balance exercise along a single axis on postural control in healthy individuals. Postural control was measured before and after a 5-min period where members of the experimental group were asked to lean their entire body forward and backward and members of the control group were asked to remain seated. A significant improvement for sway velocity, a postural control variable significantly associated with an increased risk of falls, was found in the experimental group following the body sway exercise. These data suggest that a basic exercise can rapidly improve postural control and reduce the risk of falls.

In this work we demonstrate that the 805M1 single axis analogue output accelerometer can be used to monitor honey bee activity and requires only a low cost microcontroller with an audio shield to log the data. We present accelerometer output signals demonstrating the ability to capture individual honey bee ‘whooping’ signals as well as long term amplitude monitoring, indicating the brood cycle, using this affordable measurement system.

The efficiency of solar panels is an interesting study now, due to the limitation of material capabilities used in the manufacture of solar panels. The increasing of the received radiation intensity from the sun is a way to improve the performance of solar panels. In this paper will be exposed increased efficiency of solar panels using the method of tracking the sun. The commonly used sunlight tracking is an active tracker, due to significant efficiency improvements compared to passive trackers. The active tracker consists of a single axis and a double axis, both of which use a motor as a driver. This motor is controlled using a microcontroller or a programmable logic controller (PLC). Furthermore, the automatic tracker based on microcontroller or programmable logic controller (PLC) on single axis or double axis which is implemented and can be tested in real time or periodically.

In this paper we summarize the status of bifacial photovoltaics (PV) and explain why the move to bifaciality is unavoidable when it comes to e.g., lowest electricity generation costs or agricultural PV (AgriPV). Bifacial modules—those that are sensitive to light incident from both sides—are finally available at the same price per watt peak as their standard monofacial equivalents. The reason for this is that bifacial solar cells are the result of an evolution of crystalline Si PV cell technology and, at the same time, module producers are increasingly switching to double glass modules anyway due to the improved module lifetimes, which allows them to offer longer product warrantees. We describe the general properties of the state-of-the-art bifacial module, review the different bifacial solar cells and module technologies available on the market, and summarize their average costs. Adding complexity to a module comes with the increase of possible degradation mechanisms, requiring more thorough testing, e.g., for rear side PID (Potential Induced Degradation). We show that with the use of bifacial modules in fixed tilt systems, gains in annual energy yield of up to 30% can be expected compared to the monofacial equivalent. With the combination of bifacial modules in simple single axis tracking systems, energy yield increases of more than 40% can be expected compared to fixed tilt monofacial installations. Rudimentary simulations of bifacial systems can be performed with commercially available programs. However, when more detailed and precise simulations are required, it is necessary to use more advanced programs such as those developed at several institutes. All in all, as bifacial PV—being the most cost-effective PV solution—is now becoming also bankable, it is becoming the overall best technology for electricity generation.

The article deals with the physical basis of the behavior of free abrasive grains in a single-axis vibration system. A mathematical model is made that represents the layered division of the container into layers without mixing. The established operating mode can be considered as a quasi-static state, which allowed us to determine the parameters of the speed and density of the layers of abrasive material in the working area. The optimal loading height of the working environment and the operating modes of the installation were determined.

– Panel PV(Photovoltaic) merupakan teknologi yang mengubah energi cahaya matahari menjadi energi listrik. Maka dari itu untuk mendapatkan iradiansi maksinal perlu sistem solar tracker sebagai cara untuk optimalisasi penyerapan cahaya matahari. Pada penelitian ini membahas pembuatan model simulink solar tracker menggunakan kontroler fuzzy logic. Arah sinar matahari disensor mengguanakan 2 buah sensor LDR (Light Dependent Resistor) yang selanjutnya menjadi input logika fuzy. Sistem terdiri atas 4 komponen utama yaitu PV Modul ,Mikrokontroler, motor servo, sensor LDR(Light Dependent Resistor) yang selanjutnya menjadi input logika fuzy. Output logika fuzy berupa nilai yang kemudian diumpan ke servo untuk gerakan panel secara Single Axis. Aplikasi Matlab Simulink sebagai compiler dan pembuat permodelan sistem yang nantinya akan diupload ke mikrokontroler. Arah putaran motor servo ditentukan dengan menggunakan kendali logika fuzzy. Hasil pengujian membuktikan rata-rata tegangan panel PV lebih tinggi daripada panel tanpa kendali, dengan nilai rata-rata sebesar 14,35V.

Malaysia is rapidly expanding the generation capacity of solar power through large scale solar (LSS) projects with the aim to achieve 20% renewable energy mix by 2025. This has motivated many solar industry players to explore the usage of solar PV with single axis tracker (SAT) system. However, many are still hesitant due to the lack of understanding on the comparative performance between fixed mounted solar PV with solar PV with SAT system. This paper aims to provide a comparative analysis on the performance of both systems. Simulation using PVSyst 6.83 was performed in five potential LSS sites spread across Peninsular Malaysia in Perlis, Kelantan, Pahang, Selangor and Johor with the same installed capacity of 10.32MWp. The energy yield and capacity factor for 21 years were simulated. On the average, it was found that SAT outperforms fixed mounted solar PV system by 15.08% based on their performance on their first year operation.

Gear profile grinding accuracy is often restricted by geometric errors of the rotary worktable. This paper proposes a novel approach to improve the geometric accuracy of the worktable based on single-axis motion measurement and the actual inverse kinematic model (IKM). The volumetric error model of gear profile grinding machines is first established based on homogeneous transformation matrices (HTMs) and machine kinematic chains, and the actual IKM based compensation method is then proposed to offset the position-dependent geometric errors (PDGEs) of the worktable. It directly gives explicit analytical expressions of compensated motion commands for efficient compensation. Besides, a novel PDGEs identification approach based on single-axis motion measurement with a double ball bar (DBB) is presented for the worktable. This approach has improved identification accuracy and stronger robustness as the interference error of non-targeted axes is avoided. The influence of the installation errors of the workpiece ball on measurement results and the PDGEs on gear grinding errors were discussed. The experiments verified the effectiveness of the identification approach, and the geometric accuracy tests of the worktable validated the compensation method.

The amount of power output in a solar power system depends on the intensity of solar radiation. The earth’s movements however cause changes in the intensity of solar radiation received by solar panels on the daily. Therefore, the implementation of a controller that can track the position of the sun (solar tracker) is believed to increase the power output of solar panels. This research focuses on the design of a photovoltaic panel drive system using an Android-based application as a monitoring media. The application is used to monitor the current temperature and provide a desired angle input. Based on the test results, the average power output of a fixed PV reached only 17.15 Watt, while on a single axis PV, average output reached 21.50 Watt. It can be concluded that in the single axis PV, average power output increased by more than 25% compared to the fixed PV.

Objective The aim of this study was to compare the structure of postural sway in healthy people and amputees with SACH foot (solid ankle cushion heel) and single axis foot during standing. Methods Twenty healthy, 10 amputees with single axis foot, and 10 amputees with SACH foot participated in this study. The structure of postural sway of the subjects was evaluated using approximate entropy (ApEn). Results People with SACH foot prosthesis exhibit increased regularity in postural sway compared to healthy people and people with single axis foot. Conclusion Amputees who used single axis prosthesis achieved appropriate adaptation to their prosthesis device.

The accuracy of CNC machine-tools is heavily influenced by the correct tuning of the feed drives controllers. While an initial tuning is performed by the machine-tool manufactures, in time the values have to be changed by the user in order to preserve positioning and contouring accuracy of the machine. This paper presents a model of a CNC feed drive, for a particular CNC machine-tool, but with a high degree of generality. The objective is to provide the user the necessary knowledge, together with a simple, yet accurate simulation tool, in order to assist him in the process of tuning the controllers.

Existing structural designs of various single-axis tracking systems have potentially limited energy production. This paper presents the design and performance analysis of a single-axis tracking system with a novel tracking structure. Tracking mathematic expressions based on the sun-earth geometric relationships and a predicted solar radiation model are presented. The ratio of annual solar radiation incident upon the proposed tracked panel relative to that upon a dual-axis tracked panel is 96.40%. The simulation results show that it has significant advantages over the existing single-axis tracking structures at almost all latitudes. The proposed tracking structure is a competitive choice and will provide a new perspective on enhancing solar energy yield.