User performance and attitude towards schemes for alphanumeric data entry using restricted input devices

Abstract

Results are reported from two usability trials in which a total of 14 schemes for alphanumeric data entry on television screens were evaluated. The seven schemes in the first trial used only the navigation and select keys on the TV remote control unit. The second trial used the best scheme from the first trial (slightly modified), a further six schemes using different combinations of the navigation and alphanumeric keys and a portable, infra-red keyboard. In both trials task completion rates and times were measured together with the number of keystrokes. User preferences were measured using attitude questionnaires and explicit ranking of the schemes. As expected, the keyboard was, overall, the best scheme-though not the most accurate. Where only a limited range of input keys were available, grid display schemes were preferred over menus and dynamic displays. Where an alphanumeric keypad was available on the remote control unit, a multiple press scheme was marginally preferred.     

A method for evaluating head-controlled computer input devices using Fitts' law

The discrete movement task employed in this study consisted of moving a cursor from the center of a computer display screen to circular targets located 24.4 and 110.9 mm in eight radial directions. The target diameters were 2.7, 8.1, and 24.2 mm. Performance measures included movement time, cursor path distance, and root-mean-square cursor deviation. Ten subjects with no movement disabilities were studied using a conventional mouse and a lightweight ultrasonic head-controlled computer input pointing device. Average movement time was 306 ms greater (63%) for the head-controlled pointer than for the mouse. The effect of direction on movement time for the mouse was relatively small compared with the head-controlled pointer, which was lowest at 90 and 270 deg, corresponding to head extension and head flexion, respectively. Average path distance and root mean square displacement was lowest at off-diagonal directions (0, 90, 180, and 270 deg). This methodology was also shown to be useful for evaluating performance using an alternative head-controlled input device for two subjects having cerebral palsy, and measured subtle performance improvements after providing a disabled subject with lateral torso support.     

输入饱和与姿态受限的四旋翼无人机反步姿态控制

本文针对四旋翼无人机研究了鲁棒反步姿态控制策略.由于四旋翼无人机结构复杂,其非线性数学模型难以精确建立,因此在控制器设计过程中需要综合考虑模型不确定性、未知外部干扰、输入饱和以及姿态受限等因素.针对模型中的不确定项,使用神经网络进行逼近;对于外部未知干扰,使用非线性干扰观测器进行补偿;使用双曲正切函数逼近饱和函数,解决输入饱和问题;同时使用界限Lyapunov函数设计控制器,确保姿态满足限制条件.最后,设计四旋翼无人机反步姿态控制器,并根据Lyapunov稳定性定理证明了闭环控制系统的有界稳定.仿真结果表明了所研究控制方法的有效性.     

Optimal schemes for resubmitted lot acceptance using previous defect count data

Optimal defects-per-unit inspection schemes for screening batches of manufactured material are obtained by minimizing the expected sampling effort. Nonaccepted lots may be resubmitted for resampling inspection, whereas the Poisson model is used to describe the random behavior of the number of nonconformities per sampled unit. A coefficient is presented to assess the similarity degree between the available previous information and the current inspection, and truncated gamma distributions are adopted to quantify the natural prior uncertainty about the defect rate using past count data and expert opinions. A step-by-step computational procedure is proposed to solve the underlying integer nonlinear programming problem in order to find the best resubmitted lot sampling plan with controlled expected producer and consumer risks based on previous objective and subjective knowledge. In many practical cases, the inclusion of lot resubmissions and past information into the inspection process provides substantial savings in sample size, as well as more reliable evaluations of the existing producer and consumer risks. The proposed approach allows the practitioners to consider a restricted interval for the defect rate, which is reasonable in practice and unfeasible under the frequentist perspective. Moreover, a mechanism is suggested to update the prior distribution based on past performance of the inspection plan. For illustrative purposes, the methodology developed is applied to the manufacturing of glass.     

User profiling for big social media data using standing ovation model

Multimedia Tools and Applications - Online Social Networks (OSNs) have recently been the subject of numerous studies that have attempted to develop effective methods for classifying and analyzing...     

Interacting with notebook input devices: an analysis of motor performance and users' expertise

In the present study the usability of two different types of notebook input devices was examined. The independent variables were input device (touchpad vs. mini-joystick) and user expertise (expert vs. novice state). There were 30 participants, of whom 15 were touchpad experts and the other 15 were mini-joystick experts. The experimental tasks were a point-click task (Experiment 1) and a point-drag-drop task (Experiment 2). Dependent variables were the time and accuracy of cursor control. To assess carryover effects, we had the participants complete both experiments, using not only the input device for which they were experts but also the device for which they were novices. Results showed the touchpad performance to be clearly superior to mini-joystick performance. Overall, experts showed better performance than did novices. The significant interaction of input device and expertise showed that the use of an unknown device is difficult, but only for touchpad experts, who were remarkably slower and less accurate when using a mini-joystick. Actual and potential applications of this research include an evaluation of current notebook input devices. The outcomes allow ergonomic guidelines to be derived for optimized usage and design of the mini-joystick and touchpad devices.     

Linear regression analysis for fuzzy input and output data using the extension principle

The method for obtaining the fuzzy least squares estimators with the help of the extension principle in fuzzy sets theory is proposed. The membership functions of fuzzy least squares estimators will be constructed according to the usual least squares estimators. In order to obtain the membership value of any given value taken from the fuzzy least squares estimator, optimization problems have to be solved. We also provide the methodology for evaluating the predicted fuzzy output from the given fuzzy input data.     

Microbreak length, performance, and stress in a data entry task

The effects of brief rest pauses on performance and well-being were evaluated for a highly repetitive, data entry task. Experienced data entry operators (N = 20) performed the task in a two-day experiment in a simulated office environment. Each day was divided into six, 40-min work periods. Subjects took a brief rest pause at the workstation (microbreak) in the middle of each work period. Subjects were instructed to terminate this microbreak when ready to resume work. Keystroke rate, error rate, correction rate, heart rate and heart rate variability were scored for each half of the work period. In addition, mood states before and during the work period were assessed. Microbreaks were found to average 27.4 s in duration. High ratings of fatigue and boredom during the work period were associated with longer microbreaks, suggesting that the break period was self-adjusted relative to mood state. In addition, correction rate and heart rate were lower following long microbreaks, implying that the degree of recovery was linked to the length of the microbreak. Comparison of keystroke output and correction rate before and after the microbreak, however, revealed that performance worsened after the microbreak, suggesting that subjects terminated microbreaks before complete recovery could occur.     

User identification using deep learning and human activity mobile sensor data

International Journal of Information Security - The ownership of user actions in computer and mobile applications is an important concern, especially when using shared devices. User identification...     

Physical exposure differences between children and adults when using standard and small computer input devices

By the age of five years, 75% of the children in the USA are using computers and at this age they are only one-half to two-thirds the size of and about one-fifth as strong as their adult counterparts. Fourteen children between five and eight years of age and their same-gender biological parents (giving a total of 28 subjects) were evaluated using both a standard and a smaller, child-proportional input device during standardised mouse and keyboard tasks. Typing and computer mouse performance were measured with tracking software, wrist posture was measured with an electrogoniometer and electromyography was used to measure finger flexor and extensor muscle activity in the right arm. With the small mouse, both children and adults performed the mouse task significantly faster and made significantly fewer errors. When using the standard-sized mouse and keyboard, children worked with significantly greater ulnar deviation and significantly less extension than their adult counterparts. When children used the smaller mouse, finger flexor muscle activity, finger extensor muscle activity and ulnar deviation significantly decreased, with little change in wrist extension compared to the standard mouse. No significant differences were observed between the standard and small keyboards for children or their parents. Compared to their adult counterparts, children had to apply twice the relative force, as a percentage of their maximum capacity, to activate the buttons and keys on the input devices. These measured differences may have application in the design of computer input devices for children.     

Effects of text input methods on performance in operating handheld devices between young and elderly users

This study investigated the effect of age (elderly and young participants), input methods (keyboard and handwriting), and input tools (finger and stylus) on participants’ performance in operating handheld devices. The correct ratio and execution time for device operation served as the criteria for performance evaluation. The study results revealed that the interaction between age, input method, and input tool had a significant effect on the participants’ correct ratio in operating handheld devices. For young participants, only the input method had a significant effect on the correct ratio. The keyboard provided superior results to handwriting. For the elderly participants, the interaction between input method and input tool had a significant effect on the correct ratio. When the input method was handwriting, the input tool had a significant effect on the correct ratio. Specifically, the stylus provided superior results to the finger. However, when a keyboard was used, the input tool had no significant effect on the elderly participants’ correct ratio. Concerning execution time, the interaction between age and input method had a significant effect on performance. For the young participants, the input method had a significant effect on the execution time. Specifically, the keyboard provided superior results to handwriting. However, for the elderly participants, the input method had no significant effect on the execution time.     

Physical exposure differences between children and adults when using standard and small computer input devices

By the age of five years, 75% of the children in the USA are using computers and at this age they are only one-half to two-thirds the size of and about one-fifth as strong as their adult counterparts. Fourteen children between five and eight years of age and their same-gender biological parents (giving a total of 28 subjects) were evaluated using both a standard and a smaller, child-proportional input device during standardised mouse and keyboard tasks. Typing and computer mouse performance were measured with tracking software, wrist posture was measured with an electrogoniometer and electromyography was used to measure finger flexor and extensor muscle activity in the right arm. With the small mouse, both children and adults performed the mouse task significantly faster and made significantly fewer errors. When using the standard-sized mouse and keyboard, children worked with significantly greater ulnar deviation and significantly less extension than their adult counterparts. When children used the smaller mouse, finger flexor muscle activity, finger extensor muscle activity and ulnar deviation significantly decreased, with little change in wrist extension compared to the standard mouse. No significant differences were observed between the standard and small keyboards for children or their parents. Compared to their adult counterparts, children had to apply twice the relative force, as a percentage of their maximum capacity, to activate the buttons and keys on the input devices. These measured differences may have application in the design of computer input devices for children.     

GELENT: a sequence gel entry program for keyboard and sonic digitizer input

A program is described for sequence data entry which allows flexible program control by responding to both the keyboard and a sonic digitizer concurrently. Simplification of the initialization stage of each gel reading has been achieved, in comparison with other programs.     

Robust attitude tracking control for a rigid spacecraft under input delays and actuator errors

Attitude control of a rigid spacecraft under input delays, disturbances, parameter uncertainties, actuator errors, and constraints is a challenging problem. In this paper, these problems are considered simultaneously, and a robust control approach to attitude tracking of a rigid spacecraft is exploited. The design methodology is based on three steps: (1) compensating input delays by using the backstepping technique, (2) design of a disturbance observer for the delayed system by using the super-twisting algorithm to estimate unknown internal and external disturbances, then adding a feedforward compensation law based on the estimated signal to the backstepping controller to attenuate the effects of disturbances, (3) employing a robust least-square scheme to map the specified control command on the redundant actuators in the presence of actuator error, including actuator magnitude deviation and misalignment, with regard to actuator amplitude and rate constraints. The effectiveness of the proposed algorithm is shown by various numerical simulations.     

Spatial data warehouses and spatial OLAP come towards the cloud: design and performance

Cloud computing systems handle large volumes of data by using almost unlimited computational resources, while spatial data warehouses (SDWs) are multidimensional databases that store huge volumes of both spatial data and conventional data. Cloud computing environments have been considered adequate to host voluminous databases, process analytical workloads and deliver database as a service, while spatial online analytical processing (spatial OLAP) queries issued over SDWs are intrinsically analytical. However, hosting a SDW in the cloud and processing spatial OLAP queries over such database impose novel obstacles. In this article, we introduce novel concepts as cloud SDW and spatial OLAP as a service, and afterwards detail the design of novel schemas for cloud SDW and spatial OLAP query processing over cloud SDW. Furthermore, we evaluate the performance to process spatial OLAP queries in cloud SDWs using our own query processor aided by a cloud spatial index. Moreover, we describe the cloud spatial bitmap index to improve the performance to process spatial OLAP queries in cloud SDWs, and assess it through an experimental evaluation. Results derived from our experiments revealed that such index was capable to reduce the query response time from 58.20 up to 98.89 %.     

Optimization and performance of restoration schemes for wide-area teletraffic networks

In the event of a major network outage such as a fiber cable cut, a network can experience significant deterioration of network performance. To address such a situation, a network can be equipped with restoration capacity. We present here a mathematical model and design algorithm for determination of transmission network restoration capacity. We then present models for two restoration options-connection-based restoration and load directed restoration (for restoration of bundle of circuits)-and consider their impact on a wide-area dynmic call routing teletraffic network when the restoration capacity is limited (tight). Our network simulation of failure and restoration of a dynamic call routing teletraffic network shows that the load directed approach generally performs better than the connection based approach.     

Ehlers pan-sharpening performance enhancement using HCS transform for n-band data sets

The Ehlers fusion method, which combines a standard intensity-hue-saturation (IHS) transform with fast Fourier transform filtering, is a high spectral characteristics preservation algorithm for multitemporal and multisensor data sets. However, for data sets of more than three bands, the fusion process is complicated, because only every three bands are fused repeatedly for multiple times until all bands are fused. The hyper-spherical colour sharpening (HCS) fusion method can fuse a data set with an arbitrary number of bands. The HCS approach uses a transform between an n-dimensional Cartesian space and an n-dimensional hyper-spherical space to get one single intensity component and n ? 1 angles. Moreover, from a structural point of view, the hyper-spherical colour space is very similar to the IHS colour space. Hence, we propose to combine the Ehlers fusion with an HCS transform to fuse n-band data sets with high spectral information preservation, even hyper-spectral images. A WorldView-2 data set including a panchromatic and eight multispectral bands is used for demonstrating the effectiveness and quality of the new Ehlers –HCS fusion. The WorldView-2 image covers different landscapes such as agriculture, forest, water and urban areas. The fused images are visually and quantitatively analysed for spectral preservation and spatial improvement. Pros and cons of the applied fusion methods are related to the analysed different landscapes. Overall, the Ehlers –HCS method shows the efficacy for n-band fusion.     

Evaluation methodology for performance and system economics for robotic devices

This paper presents a mathematical model for the selection and evaluation of robots, which consists of critical factors such as maximum return on investment, objective factors such as payback value to give a more complete cost perspective, and subjective factors including hardware/software, vendor performance, and internal adaptation. This evaluation procedure can be used for the selection of robots for any robot implementation, such as CAD/CAM, CIM and military applications.