@article{chen_liu_li_hsiang_jarvamard_2023, title={Motivating Reliable Collaboration for Modular Construction: Shapley Value-Based Smart Contract}, volume={39}, ISSN={["1943-5479"]}, url={https://doi.org/10.1061/JMENEA.MEENG-5428}, DOI={10.1061/JMENEA.MEENG-5428}, abstractNote={Establishing a fair benefit distribution system for construction projects, in which participants often need to work together in a highly uncertain and interrelated environment, is challenging. There is a lack of objective mechanism for construction projects to motivate reliable workflow automatically and instantly. The objective of this study is to develop Shapley value–based smart contracts to automatically assign fair rewards/penalties to motivate task-level collaborations. The research first developed a simulation model to quantify subcontractors’ marginal contributions under different coalitional scenarios. Then, the simulation results were aggregated using Shapley value to determine each participant’s reasonable rewards/penalties. Lastly, the payment was encoded in the smart contract and then deployed in the blockchain to self-enforce consensus executions. The results showed that Shapley value–based smart contracts exhibited incentives to motivate reliable contributions and enable peer negotiations to realize task-level production. The contributions of this study to the body of knowledge are (1) quantify subcontractors’ marginal contributions to the project, and (2) determine how to distribute fair collaborative outcomes when project participants can perform at different levels of effort. The incentives embedded in smart contracts can reshape project participants’ collaborative behaviors toward desired outcomes, enabling a self-manage, self-govern, and self-adjust decentralized autonomous organization.}, number={6}, journal={JOURNAL OF MANAGEMENT IN ENGINEERING}, author={Chen, Gongfan and Liu, Min and Li, Huaming and Hsiang, Simon M. and Jarvamard, Ashtad}, year={2023}, month={Nov} }
 @article{he_liu_zhang_wang_hsiang_chen_li_dai_2023, title={Space-Time-Workforce Visualization and Conditional Capacity Synthesis in Uncertainty}, volume={39}, ISSN={["1943-5479"]}, url={https://doi.org/10.1061/JMENEA.MEENG-4991}, DOI={10.1061/JMENEA.MEENG-4991}, abstractNote={Workspace, project duration, and workforce are three critical resources for construction projects. Project managers need to expend time and effort reviewing, comprehending, and coordinating these resources. However, the space–time–workforce interactions and their impact on decision-making in project scheduling are not fully known. Therefore, the objectives of this research were to understand the impact of workforce shifts on space, time, and labor cost performances, develop a three-dimensional (3D) visualization tool to reveal activity-level resource dynamics, and associate the risk aftermath with the occurrence probability to balance subjective risk tolerance and objective system reliability. This research developed a simulation model based on a case project to compare the workflow of five major specialty trades (i.e., bar placer, carpenter, scaffolder, pipefitter, and concreter) in 267 scenarios. A resource-oriented 3D visualization tool was developed to help project managers monitor project schedules. The research established a risk control framework using value-at-risk (VaR) and conditional value-at-risk (CVaR) approaches to associate extreme outcomes with their occurrence probability. Simulation results indicated that pipefitters significantly affected workspace overlap, whereas bar placers and carpenters predominantly impacted project duration. The scholarly contributions are (1) the creation of an intelligent system to generate a project schedule from workforce assignments specified by project managers, (2) development of a tool to visualize the three-way resource dynamics of workforce, time, and space on a 3D model for all possible scenarios, and (3) development of a framework for project managers to balance planning strategies between subjective risk tolerance and objective system reliability. This research provides project managers with a dynamic 3D visualization of space, time, and workforce utilization and interaction in uncertain environments, further facilitating reliable project scheduling decision-making.}, number={2}, journal={JOURNAL OF MANAGEMENT IN ENGINEERING}, author={He, Chuanni and Liu, Min and Zhang, Yuxiang and Wang, Zhigao and Hsiang, Simon M. M. and Chen, Gongfan and Li, Weiqiang and Dai, Gongfu}, year={2023}, month={Mar} }
 @article{he_liu_zhang_wang_hsiang_chen_chen_2022, title={Exploit Social Distancing in Construction Scheduling: Visualize and Optimize Space-Time-Workforce Tradeoff}, volume={38}, ISSN={["1943-5479"]}, url={https://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ME.1943-5479.0001037}, DOI={10.1061/(ASCE)ME.1943-5479.0001037}, abstractNote={The COVID pandemic has given rise to the necessity of social distancing regulations, which has brought the importance of workspace management on the construction site to an unprecedented level. Understanding and visualizing the interaction and tradeoff among space, time, and workforce is critical for construction managers to schedule and deliver projects on time. Therefore, the objectives of this research are to investigate how the critical path method (CPM) and Takt-time planning methods utilize space, time, and workforce differently, develop a tool to visualize the space–time–workforce interactions, and investigate the space–time–workforce tradeoff based on different managers' preferences. This research selected a high-rise office building project and collected 889 sets of productivity data of five specialty trades. The research built a simulation model to investigate productivity and project performance under 267 scenarios of different combinations of the three resources. A dynamic tool was then developed to visualize workspace, time, and workforce interactions. Finally, a Choquet integral–based evaluation and decision tool was developed. The simulation results show that the Takt-time planning method can reduce up to 80% of workspace overlap compared with the actual production plan with less than 20% of duration extension. The contributions to the body of knowledge are (1) creating a visual framework for managers to understand the interaction and tradeoff among space, time, and workforce quickly and accurately, and (2) developing an innovative Choquet integral approach for managers to evaluate planning strategies according to project preferences. The framework and analysis method can be adapted to other construction projects to assist managers to visualize and optimize the space–time–workforce tradeoff under uncertain project drivers. [ FROM AUTHOR] Copyright of Journal of Management in Engineering is the property of American Society of Civil Engineers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)}, number={4}, journal={JOURNAL OF MANAGEMENT IN ENGINEERING}, author={He, Chuanni and Liu, Min and Zhang, YuXiang and Wang, Zhigao and Hsiang, Simon M. and Chen, Gongfan and Chen, Jiang}, year={2022}, month={Jul} }
 @article{liu_jarvamardi_zhang_liu_hsiang_yang_yu_jiang_2021, title={Comparative Study on Perception of Causes for Construction Task Delay in China and the United States}, volume={147}, ISSN={["1943-7862"]}, DOI={10.1061/(ASCE)CO.1943-7862.0001985}, abstractNote={AbstractRapidly growing construction markets in China and the United States have provided opportunities for contractors to venture into foreign industries. To help project managers understand the f...}, number={3}, journal={JOURNAL OF CONSTRUCTION ENGINEERING AND MANAGEMENT}, author={Liu, YanChun and Jarvamardi, Ashtad and Zhang, YuXiang and Liu, Min and Hsiang, Simon M. and Yang, ShuJuan and Yu, XiuXia and Jiang, ZhiHao}, year={2021}, month={Mar} }
 @article{zhang_javanmardi_liu_yang_yu_hsiang_jiang_liu_2020, title={How Does Experience with Delay Shape Managers' Making-Do Decision: Random Forest Approach}, volume={36}, ISSN={["1943-5479"]}, DOI={10.1061/(ASCE)ME.1943-5479.0000776}, abstractNote={AbstractMaking-do, a decision to start a construction task despite knowing that its preconditions are not fully ready, is a complex dilemma for construction managers. Managers’ previous making-do d...}, number={4}, journal={JOURNAL OF MANAGEMENT IN ENGINEERING}, author={Zhang, YuXiang and Javanmardi, Ashtad and Liu, YanChun and Yang, ShuJuan and Yu, XiuXia and Hsiang, Simon M. and Jiang, ZhiHao and Liu, Min}, year={2020}, month={Jul} }
 @article{javanmardi_abbasian-hosseini_liu_hsiang_2020, title={Improving Effectiveness of Constraints Removal in Construction Planning Meetings: Information-Theoretic Approach}, volume={146}, ISSN={["1943-7862"]}, DOI={10.1061/(ASCE)CO.1943-7862.0001790}, abstractNote={AbstractTimely identification and removal of constraints is critical for improving workflow reliability. Construction project managers need to spend a significant amount of working time in various ...}, number={4}, journal={JOURNAL OF CONSTRUCTION ENGINEERING AND MANAGEMENT}, author={Javanmardi, Ashtad and Abbasian-Hosseini, S. Alireza and Liu, Min and Hsiang, Simon M.}, year={2020}, month={Apr} }
 @article{abbsaian-hosseini_liu_hsiang_2017, title={Social network analysis for construction crews}, volume={19}, ISSN={1562-3599 2331-2327}, url={http://dx.doi.org/10.1080/15623599.2017.1389642}, DOI={10.1080/15623599.2017.1389642}, abstractNote={ABSTRACT Construction crews usually have to share the limited working space with each other during construction to perform their tasks, which increases the chance of interference/conflict and productivity lost. Social network analysis (SNA) has been known as a methodology to determine the conditions of social structures by investigating the interdependencies among a set of actors. The impact of jobsite social network on the performance of the crews has not been well documented in previous research. This research proposes an analytical approach by combining SNA and work plan variation analysis to (1) quantify the influence construction crews receive from jobsite social network, and (2) explore the impact of jobsite social network on the crews’ performance particularly on their work plan variation through a case study. The results indicated that there is a positive monotonic association between each of the centrality indices (representing network influence on each crew) and each of the work plan variability indices (representing crew's performance). The more influences a crew receives form the network, the more work plan variation it will have. A better understanding of the existing jobsite interdependencies will help project managers to control it through better planning and leadership, consequently increasing jobsite productivity.}, number={2}, journal={International Journal of Construction Management}, publisher={Informa UK Limited}, author={Abbsaian-Hosseini, S. Alireza and Liu, Min and Hsiang, Simon M.}, year={2017}, month={Nov}, pages={113–127} }
 @article{wambeke_hsiang_liu_2011, title={Causes of Variation in Construction Project Task Starting Times and Duration}, volume={137}, ISSN={0733-9364 1943-7862}, url={http://dx.doi.org/10.1061/(asce)co.1943-7862.0000342}, DOI={10.1061/(asce)co.1943-7862.0000342}, abstractNote={In this research, variation is defined as the time difference between what was planned and what actually happened in terms of task starting times and duration. Variation in construction tasks is important as it can impact productivity performance. Construction projects consist of a large number of interdependent tasks. When the starting time and/or duration of one task varies, it can affect other downstream tasks and result in disruptions to the schedule and/or decreased productivity. The construction process is complex and involves numerous people with different levels of responsibility, which makes identifying the root causes of the variation difficult. A nationwide survey was administered to workers, foremen, and project managers to identify the most prevalent causes and magnitude of both starting time and task duration variation. Fifty individual causes of variation were divided into eight categories: prerequisite work, detailed design/working method, labor force, tools and equipment, material and components, work/job site conditions, management/supervision/information flow, and weather or external conditions. This research examined the similarities and differences in perceptions between craft workers, foremen, and project managers in terms of starting time and task duration variation. The top eight causes of starting time variation and top nine causes of task duration variation were identified. The research also quantitatively analyzed the underlying structure of the causes of variation using factor analysis. This was done by grouping the 50 individual causes into nine orthogonal factors that represent the underlying structure of the affecting causes. The findings will help construction project managers and field managers focus on the root causes of variation during planning in order to develop effective strategies to reduce variation and improve project productivity performance.}, number={9}, journal={Journal of Construction Engineering and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Wambeke, Brad W. and Hsiang, Simon M. and Liu, Min}, year={2011}, month={Sep}, pages={663–677} }
 @article{wang_hsiang_2011, title={Modeling trade-off between time-optimal and minimum energy in saccade main sequence}, volume={104}, ISSN={["1432-0770"]}, DOI={10.1007/s00422-011-0420-3}, abstractNote={Saccadic eye movement is highly stereotyped and commonly believed to be governed by an open-loop control mechanism. We propose a principle combining time-optimal and minimum control energy criteria to account for the saccade main sequence as observed from empirical data. The model prediction revealed that the weighting factor of the energy conservation becomes more dominant than the time-optimal when the saccade amplitude is large. We demonstrate that the proposed model is a general form synthesizing the time-optimum, minimum torque change, and minimum control effort models. In addition, we show the connection between our model and the stochastic minimum variance models from the aspect of optimization.}, number={1-2}, journal={BIOLOGICAL CYBERNETICS}, author={Wang, Xuezhong and Hsiang, Simon M.}, year={2011}, month={Feb}, pages={65–73} }
 @article{davis_maclagan_karakostas_hsiang_shenk_2011, title={Watching What You Say: Walking and Conversing in Dementia Preliminary Studies}, volume={27}, ISSN={["0882-7524"]}, DOI={10.1097/tgr.0b013e31821e58db}, abstractNote={This article reports 3 pilot studies of cognitively impaired (CI) persons responding to different types of questions. Pilot 1 analyzed responses of 7 people at high CI risk and 7 people at low CI risk to questions asked during seated conversation. High-risk participants paused longer before responding. Pilot 2 identifi ed types of questions asked from 1 participant in seated conversations with 2 interviewers and analyzed her responses. Pilot 3 introduced a dual task, walking while answering an unexpected question. The CI participants paused longer before responding than controls. A subset of 6 time-distance parameters distinguished gait of the 2 participant groups.}, number={4}, journal={TOPICS IN GERIATRIC REHABILITATION}, author={Davis, Boyd H. and Maclagan, Margaret and Karakostas, Tasos and Hsiang, Simon and Shenk, Dena}, year={2011}, pages={268–277} }
 @article{coker_karakostas_dodds_hsiang_2010, title={Gait characteristics of children with hemiplegic cerebral palsy before and after modified constraint-induced movement therapy}, volume={32}, ISSN={["1464-5165"]}, DOI={10.3109/09638280903171592}, abstractNote={This investigation assessed selected gait parameters of children with hemiparesis before and after participation in a modified constraint-induced movement therapy program (mCIMT). Recent advances in the understanding of the relationship between mCIMT and cortical reorganization supports the use of upper-extremity mCIMT to treat lower extremity deficits. However, the effects of mCIMT on the gait patterns of children with hemiparesis remain unclear. Twelve preschool children participated in a mCIMT program for 5 consecutive days, 6 h each day. Pre- and post-intervention data, on the temporal-spatial aspects of gait, were collected with the GAITRite walkway. Data were analyzed using a repeated measures generalized linear model. Base of support decreased significantly (p < 0.001) following treatment and improvements were noted in most other gait descriptors. The results of this study suggest that mCIMT can increase stability and improve the overall gait pattern. This study provides a new dimension in the effects of pediatric mCIMT programs and could begin to shift the focus of this intervention to remediation of lower extremity deficits. Additional studies with a longitudinal follow-up focus to determine the long-term effects of mCIMT on walking balance and stability would be beneficial.}, number={5}, journal={DISABILITY AND REHABILITATION}, author={Coker, Patricia and Karakostas, Tasos and Dodds, Cindy and Hsiang, Simon}, year={2010}, pages={402–408} }
 @article{chang_mcgorry_lin_xu_hsiang_2010, title={Prediction accuracy in estimating joint angle trajectories using a video posture coding method for sagittal lifting tasks}, volume={53}, ISSN={["0014-0139"]}, DOI={10.1080/00140139.2010.489963}, abstractNote={This study investigated prediction accuracy of a video posture coding method for lifting joint trajectory estimation. From three filming angles, the coder selected four key snapshots, identified joint angles and then a prediction program estimated the joint trajectories over the course of a lift. Results revealed a limited range of differences of joint angles (elbow, shoulder, hip, knee, ankle) between the manual coding method and the electromagnetic motion tracking system approach. Lifting range significantly affected estimate accuracy for all joints and camcorder filming angle had a significant effect on all joints but the hip. Joint trajectory predictions were more accurate for knuckle-to-shoulder lifts than for floor-to-shoulder or floor-to-knuckle lifts with average root mean square errors (RMSE) of 8.65°, 11.15° and 11.93°, respectively. Accuracy was also greater for the filming angles orthogonal to the participant's sagittal plane (RMSE = 9.97°) as compared to filming angles of 45° (RMSE = 11.01°) or 135° (10.71°). The effects of lifting speed and loading conditions were minimal. To further increase prediction accuracy, improved prediction algorithms and/or better posture matching methods should be investigated. Statement of Relevance: Observation and classification of postures are common steps in risk assessment of manual materials handling tasks. The ability to accurately predict lifting patterns through video coding can provide ergonomists with greater resolution in characterising or assessing the lifting tasks than evaluation based solely on sampling with a single lifting posture event.}, number={8}, journal={ERGONOMICS}, author={Chang, Chien-Chi and McGorry, Raymond W. and Lin, Jia-hua and Xu, Xu and Hsiang, Simon M.}, year={2010}, pages={1039–1047} }
 @article{dong_hsiang_smith_2009, title={An Optimal-Control Model of Vision-Gait Interaction in a Virtual Walkway}, volume={39}, ISSN={["1083-4419"]}, DOI={10.1109/TSMCB.2008.2003427}, abstractNote={The specific aim of this paper is to model the vision-posture coupling behavior, which is important for astronauts to stabilize their locomotion in partial gravities as the national aeronautics and space administration plans for manned missions to the moon and mars . As such, an optimal scheme is assumed in postural-control processes to stabilize visual optical flows. An experiment was conducted, in which human subjects attended a visual-gait tracking task. In tracking control, head position errors can be used to regulate inputs so that appropriate compensatory changes can be obtained. The ldquooptimalrdquo scheme describes a compromise between postural adjusting efforts and tracking errors. The results show that the proposed optimal-control model describes the gait tracking process more reliably than McRuer's crossover model of the human-plant compensatory behaviors. In practice, if the tracking goal is to be roughly right rather than precisely wrong, this paper also provides the experimental data regarding the human tolerance and achievable performance under various unloading conditions and tracking difficulties. This information and related experimental setup could also be applied to postsurgery gait rehabilitation.}, number={1}, journal={IEEE TRANSACTIONS ON SYSTEMS MAN AND CYBERNETICS PART B-CYBERNETICS}, author={Dong, Haining and Hsiang, Simon M. and Smith, James L.}, year={2009}, month={Feb}, pages={156–166} }
 @article{rivero_pantoya_rajamani_hsiang_2009, title={Correlation of reactant particle size on residual stresses of nanostructured NiAl generated by self-propagating high-temperature synthesis}, volume={24}, ISSN={["2044-5326"]}, DOI={10.1557/JMR.2009.0240}, abstractNote={This investigation analyzed the effect of reactant particle size on the stress development characteristics of NiAl synthesized through self-propagating high temperature synthesis. Four sample combinations of NiAl were synthesized based on initial particle diameters of the reactants: (i) 10 μm Al and 10 μm Ni (S1), (ii) 10 μm Al and 100 nm Ni (S2), (iii) 50 nm Al and 10 μm Ni (S3), and (iv) 50 nm Al and 100 nm Ni (S4). Characterization of NiAl was performed by parallel comparison of the distribution of residual stresses of the samples prior to and after the reaction. Residual stresses were quantified using x-ray diffraction. Upon characterization it was found that combinations S1, S2, and S3 exhibited tensile residual stresses, while combination S4 exhibited compressive residual stresses. Statistical analysis confirmed that self-propagating high temperature synthesis products derived from nanoparticle reactant sizes exhibited compressive residual stresses offering improved fatigue resistance in composite production.}, number={6}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Rivero, Iris V. and Pantoya, Michelle L. and Rajamani, Karthik and Hsiang, Simon M.}, year={2009}, month={Jun}, pages={2079–2088} }
 @inproceedings{hong_hsiang_xu_2009, title={Human-machine co-construct intelligence on horizon year load in long term spatial load forecasting}, DOI={10.1109/pes.2009.5275308}, abstractNote={Horizon year load (HYL) is an important parameter in load forecasting algorithms that involve the Gompertz functions. Land use information has been utilized to determine HYL by computerized program. However, this approach fails when computer tries to seek optimal solution but ignores the physical meaning of the data, which can be overcome by the planners. This paper proposes and implements a methodology to determine horizon year load using land use information and planners' domain knowledge. The proposed methodology has been implemented and applied to several US utility companies to calculate the HYL of the small areas in the service territory. The resulting HYL has been used to drive the long-term electric load growth forecasting and to get satisfying forecast.}, booktitle={2009 ieee power & energy society general meeting, vols 1-8}, author={Hong, T. and Hsiang, S. M. and Xu, L.}, year={2009}, pages={1030–1035} }
 @article{karabelchtchikova_hsiang_sisson_2009, title={Multi-objective optimisation of gas carburising process in batch furnaces with endothermic carburising atmosphere}, volume={25}, ISSN={["1743-2944"]}, DOI={10.1179/174329408X315634}, abstractNote={ A methodology for multi-objective optimisation of gas carburising heat treatment has been developed in terms of cost, cycle time and quality of carburised parts. The optimisation strategy is based on: modelling the effect of process parameters (carbon potential, temperature and time) on the mass transfer coefficient and carbon diffusivity in austenite, correlating the observed variations in the process parameters on the carburising kinetics, and developing a robust multiobjective optimisation technique to achieve the desired case depth with minimum cost and minimum case depth variation. The tradeoff between these two objective functions corresponded to carburising at 938·5°C and carbon potential of 1·14 wt-%C. This combination produced the target case depth of 0·6 mm with corresponding ±0·05 mm case depth variation and minimum total cycle cost. Overall, application of this multi-objective optimisation will result in significant energy reduction by shortening cycle time and thereby enhancing furnace capacity. }, number={1}, journal={SURFACE ENGINEERING}, author={Karabelchtchikova, O. and Hsiang, S. M. and Sisson, R. D., Jr.}, year={2009}, month={Jan}, pages={43–49} }
 @inproceedings{hsiang_2009, title={Risk assessment for emergency management}, booktitle={International Symposium on Emergency Management 2009 (ISEM'09)}, author={Hsiang, S. M.}, year={2009}, pages={587–591} }
 @article{xu_hsiang_mirka_2009, title={The effects of a suspended-load backpack on gait}, volume={29}, ISSN={["1879-2219"]}, DOI={10.1016/j.gaitpost.2008.06.008}, abstractNote={A suspended-load backpack is a device that is designed to capture the mechanical energy created as a suspended backpack load oscillates vertically on the back during gait. The objective of the current study was to evaluate the effect of a suspended-load backpack system on selected temporal and kinetics parameters describing gait. Nine male participants carried a suspended-load backpack as they walked on an instrumented treadmill with varied levels of load (no backpack, 22.5 kg, and 29.3 kg) and walking speed (1.16 m/s, 1.43 m/s, 1.70 m/s). As the participants performed this treadmill task, ground reaction forces were collected from an instrumented treadmill system. From these data, temporal variables (cycle time, single support time, and double support time) and kinetic variables (normalized weight acceptance force, normalized push-off force, and normalized mid-stance force) were derived. The results showed that the response of the temporal variables were consistent with previous studies of conventional (i.e. stable load) backpacks. The response of the normalized push-off force, however, showed that increasing walking speed significantly (p<0.05) decreased the magnitude of this force, a result contrary to the literature concerning conventional backpacks where this force has been shown to significantly increase. Further evaluation revealed that this reduction in force was the result of a phase shift between the movement of the carried load and the movement of the torso. This suggests that the motion of the load in a suspended-load backpack influences the gait biomechanics and should be considered as this technology advances.}, number={1}, journal={GAIT & POSTURE}, author={Xu, Xu and Hsiang, Simon M. and Mirka, Gary A.}, year={2009}, month={Jan}, pages={151–153} }
 @article{xu_hsiang_mirka_2008, title={Coordination indices between lifting kinematics and kinetics}, volume={38}, ISSN={["1872-8219"]}, DOI={10.1016/j.ergon.2008.02.008}, abstractNote={During a lifting task the movement of the trunk can account for the majority of the external moment about the ankle. Though the angle of trunk flexion and the external moment about the ankles are roughly correlated, this correlation can be reduced by various segmental dynamics and momentums with the upper/lower extremities. Two methods are proposed in this technical note for describing the relationship between the kinematics and the kinetics of a lifting motion. The first relies on the phase plane analysis technique and explores the relative phase angle between the kinematic characteristics of lifting motion (i.e., trunk motion in the sagittal plane) and the kinetic characteristics of lifting motion (i.e., the net external moment). The second technique employs the moving correlation technique that assesses the level of coordination between the net external moment and the angle of the torso in the sagittal plane. In this paper, these methods are applied to a dataset of lifting motions of obese and normal weight participants to explore the utility of these modeling approaches on the assessment of potential risk in the lifting task due to obesity. Quantifying the coordination between the movement of the trunk and the net external moment can be helpful in understanding the lifting techniques that may place the lifter at higher risk of developing a low back injury.}, number={11-12}, journal={INTERNATIONAL JOURNAL OF INDUSTRIAL ERGONOMICS}, author={Xu, Xu and Hsiang, Simon M. and Mirka, Gary A.}, year={2008}, pages={1062–1066} }
 @article{karabelchtchikova_riuero_hsiang_2008, title={Modeling of residual stress distribution in D2 steel via grinding dynamics using a second-order damping system}, volume={198}, ISSN={["0924-0136"]}, DOI={10.1016/j.jmatprotec.2007.07.006}, abstractNote={A second-order system is proposed to model residual stress distributions in D2 tool steel under various heat treatment procedures and grinding dynamics. The study was motivated to predict the magnitude of the residual stress, tensile peak location, and to establish the nonlinear superposition relationship in the residual stress distribution due to the number of grinding passes. The grinding dynamics was represented as a lumped system composed of a spring-mass-damper of the grinding machine and a damper-stiffness of the workpiece. A nested factorial experiment of 18 conditions with 3 levels of tempering, 2 levels of grinding conditions and 3 multipass grinding levels was used for the model development and validation. The parameters of each condition were then optimized by using auto-regressive system identification. The proposed model depicts changes of the complex experimental treatment conditions and estimates in a precise and parsimonious way the corresponding change in the subsurface residual stress distribution. With only one parameter involved, the model facilitates conceptual progress in the residual stress superposition; the prediction elucidates grinding dynamics and supports a theory of the heat treatment and grinding effects on the material characteristics.}, number={1-3}, journal={JOURNAL OF MATERIALS PROCESSING TECHNOLOGY}, author={Karabelchtchikova, Olga and Riuero, Iris V. and Hsiang, Simon M.}, year={2008}, month={Mar}, pages={313–322} }
 @article{kaber_alexander_stelzer_kim_kaufmann_hsiang_2008, title={Perceived Clutter in Advanced Cockpit Displays: Measurement and Modeling with Experienced Pilots}, volume={79}, ISSN={["1943-4448"]}, DOI={10.3357/ASEM.2319.2008}, abstractNote={INTRODUCTION
Synthetic and enhanced vision systems (SVS and EVS) are being introduced into the cockpit to promote safety under workload conditions. Integration of existing iconic imagery with SVS and EVS displays may lead to perceptions of clutter. This research evaluated head-up display (HUD) features, including SVS, EVS, traffic collision avoidance system symbology, flight pathway (TUNNEL) guidance, and different primary flight display symbol sets, on pilot perceptions of clutter. A perceptual decomposition of the construct of clutter was also conducted.


METHOD
During a simulated landing, 4 expert pilots viewed images of 16 HUD configurations. Pilots rated clutter for each image and the utility of pairs of terms for describing clutter.


RESULTS
Results revealed all HUD features and two-way interactions to be significant in perceived clutter. Ratings increased with additional features. The presence of EVS, TUNNEL, and an expanded symbol set contributed the most. Regression models were developed to predict the likelihood of clutter ratings based on pilot perceptions of display characteristics. Pairs of terms found to have the greatest use for describing clutter included "redundant/orthogonal," "monochromatic/colorful," "salient/not salient," "safe/unsafe," and "dense/sparse" (in that order). A factor analysis revealed underlying display qualities explaining approximately 78% of variability in perceived clutter, including global density, feature similarity, feature clarity, and the dynamic nature of displays. These qualities corresponded with the display descriptor terms plus the terms "static/dynamic."


DISCUSSION
The study provided information on the relationship of display features and pilot perceptions of clutter. We identified terminology pilots use to describe clutter and latent display variables that drive perceived clutter.}, number={11}, journal={AVIATION SPACE AND ENVIRONMENTAL MEDICINE}, author={Kaber, David B. and Alexander, Amy L. and Stelzer, Emily M. and Kim, Sang-Hwan and Kaufmann, Karl and Hsiang, Simon}, year={2008}, month={Nov}, pages={1007–1018} }
 @article{xu_mirka_hsiang_2008, title={The effects of obesity on lifting performance}, volume={39}, ISSN={["0003-6870"]}, DOI={10.1016/j.apergo.2007.02.001}, abstractNote={Obesity in the workforce is a growing problem worldwide. While the implications of this trend for biomechanical loading of the musculoskeletal system seem fairly straightforward, the evidence of a clear link between low back pain (LBP) and body mass index (BMI) (calculated as whole body mass in kilograms divided by the square of stature in meters) has not been shown in the epidemiology literature addressing this topic. The approach pursued in the current study was to evaluate the lifting kinematics and ground reaction forces of a group of 12 subjects -- six with a BMI of less than 25 kg/m(2) (normal weight) and six with a BMI of greater than 30 kg/m(2) (obese). These subjects performed a series of free dynamic lifting tasks with varied levels of load (10% and 25% of capacity) and symmetry (sagittally symmetric and 45 degrees asymmetric). The results showed that BMI had a significant effect (p<0.05) on trunk kinematics with the high BMI group exhibiting higher peak transverse plane (twisting) velocity (59% higher) and acceleration (57% higher), and exhibiting higher peak sagittal plane velocity (30% higher) and acceleration (51% higher). When normalized to body weight, there were no significant differences in the ground reaction forces between the two groups. This study provides quantitative data describing lifting task performance differences between people of differing BMI levels and may help to explain why there is no conclusive epidemiological evidence of a relationship between BMI and LBP.}, number={1}, journal={APPLIED ERGONOMICS}, author={Xu, Xu and Mirka, Gary A. and Hsiang, Simon M.}, year={2008}, month={Jan}, pages={93–98} }
 @article{karakostas_hsiang_sarantopoulos_krause_2007, title={Dynamic loading performance of fasciocutaneous flaps and implications for gait}, volume={22}, ISSN={["0268-0033"]}, DOI={10.1016/j.clinbiomech.2006.11.012}, abstractNote={Background Recent advancements in microsurgery allow the free tissue transfer for reconstruction of soft-tissue defects on the plantar surface of the foot. Fasciocutaneous flaps are one available option to the reconstructive surgeon. However, their functional weight-bearing capabilities have never been adequately evaluated. This study investigated the dynamic loading performance of selected fasciocutaneous flaps during walking using instrumented gait analysis. Methods We investigated 6 feet with reconstructed heels along with their contralateral normal feet. A control group of normals was included also. Time–distance, ground reaction force parameters and plantar foot pressure distribution were evaluated. Data were normalized to account for anthropometric variations. A series of t-tests were used to investigate contrasts. Findings Walking velocity of injured subjects was decreased (P < 0.0001). Step length and single limb support were the shortest for the involved feet (P < 0.04). Double limb support and swing were the longest (P < 0.0002). The reconstructed heels sustained high pressures (P < 0.05) and vertical loadings underlining their functional weight-bearing capabilities. However, the walking patterns implemented by the injured subjects resulted in reduced anterior–posterior shear forces that could help maintain the integrity of the shear plane at the graft-recipient bed interface. Interpretation The dynamic loading capabilities of the fasciocutaneous flaps make it an effective means for restoring functional gait. Patients implement gait patterns that result in primarily decreasing shear forces. Consequently, the fasciocutaneous flaps should be included in the surgeons’ armentarium as a plausible reconstructive means for soft-tissue defects on the plantar surface of the foot.}, number={4}, journal={CLINICAL BIOMECHANICS}, author={Karakostas, Tasos and Hsiang, Simon M. and Sarantopoulos, Costas and Krause, James}, year={2007}, month={May}, pages={478–485} }