Geometrical analysis and design of a motion transmitting element for mobile vehicles

The range of speed or torque of motors is limited to some degree. Industrial vehicles working in factories are required to output a large force when they carry loads, and also to move with high velocity when they move to their destination. However, it is impossible to realize both those requirements if a conventional reduction device is used. Velocity variation devices using gears are widely used to change the velocity ratio between the input and output shafts. However, the motion transmission from the input shaft to the output shaft is interrupted during the velocity ratio variation process. In order to solve this problem, a velocity variation method that can transmit motion continuously is proposed, in which a motion transmitting element is used. In this report, a motion transmitting element using the geometrical analysis method is proposed, a method of expressing the curve using dispersed points is proposed, and a method of calculating the inclination and the distances along the curve is developed. Based on the proposed methods, the geometrical form of the transmitting element is analyzed.     

Comparative analysis of direct-absorption parabolic-trough solar collectors considering concentric nanofluid segmentation

Nanofluids have been actively used in direct-absorption solar collectors. In a direct-absorption parabolic-trough solar collector (DAPTSC) for medium-high temperature regime, the nanofluids used to be contained in a transparent glass receiver located at the focal line of a parabolic mirror so that the solar radiation is concentrated to the glass receiver and absorbed volumetrically inside the collector. In order to further increase the thermal efficiency of a DAPTSC, we propose to insert an extra glass tube inside the nanofluid so that the nanofluid is separated into two concentric segmentations (ie, an inner section and an outer section), and apply a nanofluid of lower concentration in the outer section while a nanofluid of a higher concentration in the inner section. The proposed idea is numerically tested on four pairs of DAPTSCs (the variants obtained depending on whether there is a vacuum envelope and whether there is a reflective semicylindrical coating on the receiver). The results show that at the same particle concentration parameter, the DAPTSCs with two concentric segmentations of nanofluids outperform those with one uniform nanofluid for all configurations considered in this work. For a transparent case without an envelope, this efficiency increase is as high as 12.5% point when the inlet temperature is 350 K. In addition, parametric studies are performed for this best configuration to evaluate the effect of absorption coefficient, mass flow rate, collector length, solar irradiance, and convection heat transfer coefficient on the collector performance.     

Integration of Adaptable and Adaptive Approaches for Interface Personalization Through Collaborative Menu

This article examines different user-system collaboration models in the adaptation of a menu interface. Four collaboration models were implemented on a prototype of mobile phone menu: (a) basic collaboration with no system support (for user adaptation) and no user control (over system adaptation), (b) system support only, (c) user control only, and (d) system support plus user control. The prototype mobile phone menu includes a hotlist (a quickly accessible collection of menu items) as well as a hierarchical menu. The hotlist is collaborative, because it combines adaptable and adaptive approaches by allowing both the user and the system to manage the items in it. A controlled experiment compared different types of collaborative menus in order to investigate the effects of system support and user control. Twenty participants performed menu selection tasks in the experiment, and both performance and subjective measures were taken. The results showed that, in a certain condition, the system support and the user control improved the user performance when applied independently, but their effects were not additive. Although the effects disappeared when the selection frequency distribution changed, the system support was preferred by most of the users. The advantages and disadvantages of the collaborative menus and implications for the adaptation of menus are discussed.     

Complementary menus: Combining adaptable and adaptive approaches for menu interface

This study proposes a method of coupling adaptable and adaptive approaches to the design of menus. The proposed complementary menu types incorporate both adaptability and adaptivity by dividing and allocating menu adaptation roles to the user and the system. Four different types of interface adaptation (i.e., adaptable with/without system support and adaptive with/without user control) were defined. They were implemented in a hypothetical prototype mobile phone via a hotlist (an additional collection of quickly accessible items). A controlled lab experiment was conducted to compare the menu types and investigate the effects of the system support in the adaptable menus and the user control in the adaptive menus. Twenty subjects participated in the experiment and performed menu selection tasks. Both performance and user satisfaction measures were collected. The results showed that adaptable and adaptive menus were superior to the traditional one in terms of both performance and user satisfaction. Providing system support to the adaptable menu not only increased the users’ perception of the efficiency of selection, but also reduced the menu adaptation time. Important implications for the design of menus are described and valuable insights into the menu interface adaptation were gained from the quantitative and qualitative analyses of the experimental results.

Relevance to industry

The evaluation experiment conducted in this study may provide valuable information to designers of adaptive or adaptable menus. Adding system support to adaptable menu would be an attractive option to consider. Also, the results of a user survey provide useful information to the practitioners in mobile phone industry on the features users accessed most frequently.     

Microthermogravimetry using a microcantilever hot plate with integrated temperature-compensated piezoresistive strain sensors

This paper reports thermogravimetric analysis of nanogram samples of paraffin using a microcantilever hot plate. The microcantilever hot plate has an integrated temperature-controlled heater and integrated temperature-compensated strain-sensing piezoresistors. The microcantilever vibration amplitude was measured using either a laser and a position sensitive photodiode, or using the piezoresistors. The cantilever resonance was measured as the cantilever was heated, such that the analyte mass could be measured as a function of temperature. Both optical and piezoresistive methods were employed to generate thermogravimetric curves for analytes in the range of 1-3 ng, and the results of the two methods compared well.     

Analytic approach to analyzing the performance of membrane dehumidification by pervaporation

As life quality has been greatly improved recently, the importance of humidity control has increased. Various kinds of humidifiers and dehumidifiers have been developed and utilized widely in our daily lives and industrial processes. In this work, we focused on dehumidification facilitated by a pervaporation system that employs a nonporous membrane. The system mainly consists of two parallel chambers separated by the membrane and a vacuum pump that constantly drives moisture removal. The membrane-pump couple sets out a vapor concentration gradient across the membrane to permeate water vapors from the feed chamber of ambient wet air to the low-pressure permeate. The experiments were performed in a constant temperature and humidity chamber to supply the constant concentration of vapor to the feed chamber. We measured the outlet humidity and the water vapor transport rate, the mass of vapor permeated through the membrane, under various experimental conditions of different feed flow rates and feed chamber heights. As the flow rate increases, the outlet humidity is decreased, whereas the water vapor transport rate is increased. However, they are independent of the height in our experiment range. Combining the mass transport theory of the membrane and volume conservation of an infinitesimal control volume, we have established theories of the outlet humidity and the water vapor transport rate. The experimental data points are entirely consistent with our theory curves. Comparing the experimental results to the theories, we also have derived the membrane coefficient.

     

High precision particle mass sensing using microchannel resonators in the second vibration mode

An intrinsic uncertainty in particle mass sensing with the suspended microchannel resonator results from variation in a particle's position near the free end of the resonator. To circumvent this error we employ the second flexural bending mode. This mode exhibits additional frequency peaks while particles pass over the antinode, a point where the frequency shift is insensitive to the lateral position of the particle. We measure polystyrene beads with the first and second modes and confirm that the second mode sensing provides a narrower mass histogram. For 3 μm diameter beads, second mode sensing at the antinode improves the coefficient of variation in buoyant mass from 1.76% to 1.05% for population measurements and from 1.40% to 0.53% for a single trapped particle.     

Topography imaging with a heated atomic force microscope cantilever in tapping mode

This article describes tapping mode atomic force microscopy (AFM) using a heated AFM cantilever. The electrical and thermal responses of the cantilever were investigated while the cantilever oscillated in free space or was in intermittent contact with a surface. The cantilever oscillates at its mechanical resonant frequency, 70.36 kHz, which is much faster than its thermal time constant of 300 micros, and so the cantilever operates in thermal steady state. The thermal impedance between the cantilever heater and the sample was measured through the cantilever temperature signal. Topographical imaging was performed on silicon calibration gratings of height 20 and 100 nm. The obtained topography sensitivity is as high as 200 microVnm and the resolution is as good as 0.5 nmHz(1/2), depending on the cantilever power. The cantilever heating power ranges 0-7 mW, which corresponds to a temperature range of 25-700 degrees C. The imaging was performed entirely using the cantilever thermal signal and no laser or other optics was required. As in conventional AFM, the tapping mode operation demonstrated here can suppress imaging artifacts and enable imaging of soft samples.     

Frequency-Dependent Electrical and Thermal Response of Heated Atomic Force Microscope Cantilevers

This paper investigates the electrical and thermal response of the heated atomic force microscope (AFM) cantilevers in the frequency range from 10 Hz to 1 MHz. Spectrum analysis of the cantilever voltage response to periodic heating distinguishes different thermal behaviors of the cantilever in the frequency domain: the cantilever voltage at low frequencies is modulated by higher-order harmonics, and at high frequencies it oscillates with 1-omega only. A simple model facilitates the understanding of complicated electrical and thermal behaviors in the cantilever, thus, it is possible to determine the cantilever temperature. The calculation predicts that temperature oscillation is restricted to the heater region when the cantilever is operated at about 10 kHz, suggesting that the periodic-heating operation of the cantilever may be employed for highly sensitive thermal metrology