A. James Clark School of Engineering
Permanent URI for this communityhttp://hdl.handle.net/1903/1654
The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
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Item A STUDY OF GENDER DIVERSITY IN U.S. ARCHITECTURE, ENGINEERING, AND CONSTRUCTION (AEC) INDUSTRY LEADERSHIP(2023) Hickey, Paul Joseph; Cui, Qingbin; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Anecdotally, men dominate the Architecture, Engineering, and Construction (AEC) field. This study contributes to the body of knowledge by quantifying the gender composition of the c-suite, identifying differences in career paths between women and men, and gathering in-depth information on women engineering executives’ professional stories. Using the industry recognized Engineering News Record (ENR) Top 400 largest companies, initial phase of this research found women filled 3.9% of engineering executive positions in 2019, reducing to 3.5% in 2021. However, certain sub-segments, highlighted by firms with a public commitment to diversity, ENR Top 100 Green companies, and larger organizations, offer more opportunities to women. Exploring further into individual and collective career paths, researchers applied web scraping algorithms to extract LinkedIn data for 2,857 industry leaders. Data found that women work for more companies (+56%), hold more positions (+19%), earn more advanced degrees (53.9% to 31.2%), assemble larger professional networks (+14%), yet remain significantly underrepresented (-83%). Confirming a difference between the career paths of women and men, Machine Learning (ML) modeling predicted profile genders with 98.95% training sample and 89.53% testing sample accuracy. Final stage of research incorporates interviews with women engineering executives, seeking to learn about pathways and barriers in their respective and collective professional journeys and test the findings from the initial two phases of this study. An overriding theme throughout the progressive study, recommendations for increasing women’s representation include directed Science, Technology, Engineering, and Math (STEM) scholarships for young girls, targeted recruiting of women, establishing mentoring relationships, and creating nurturing cultures to retain early and mid-career women.Item A Complexity-Based Approach to Intra-Organizational Team Selection(2013) Hsu, Shu-Chien; Cui, Qingbin; Skibniewski, Miroslaw; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Early studies recognized the significance of team's work capacity and suggested the selection of team members based on individual skills and performance in alignment with task characteristics. The equitable team selection method, for example, assigns people to different tasks with even skill distributions for the best overall performance. Recent advancement in organization science also identifies the importance of contextual skills. However, work teams are complex adaptive systems with interdependence between workers and social environment, and exhibit surprising, nonlinear behavior. Optimizing individual stages without taking organizational complexity into account is unlikely to yield a high performing new combination of teams. The objectives of this study can be stated as: a) Utilizing complex system theory to better understand the processes of team selection including forming teams with considering worker's interdependence and replacing the unsuitable members through a time frame; b) Comparing different team selection methods, including random selection, equity method, using knowledge of interdependence in different economic conditions through simulation; c) Comparing different policies of replacing members of teams. This study utilizes a computational model to understand the complexity of project team selection and to examine how diversity of capability and interdependence between workers to effect team performance in different economic conditions. The NK model, a widely used theory for complex systems is utilized here to illustrate the worker's interdependence and fed into an Agent-Based Model. This study uses a small design firm as a case implementation to examine the performance of a variety of team selection approaches and replacement policies. Project data, task assignment, and individual and team performance information were collected for the period of 2009-2011. The simulation results show that while the equity selection method can increase the diversity of capabilities of teams, the net performance is often worse than optimizing worker interdependencies. This study suggests that managers should protect their higher-performing workers with minimal interdependence disruption when they considered team selection. Thus taking the advantages and disadvantages of all three policies into account, transferring low contributors or least supported members are recommended to be enacted before hiring new workers to avoid this last policy's especially large additional costs.Item COOPERATIVE COMMUNICATION WITH WIRELESS NETWORK CODING(2013) Guan, Wei; Liu, K. J. Ray; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Cooperative communication is a new communication paradigm that allows multiple transceivers to collaborate as a cluster for data transmission, and such clustering could greatly improve the transmission quality due to cooperative diversity. For conventional cooperation protocols, each cooperating device uses orthogonal channels to relay different messages for mitigating co-channel interference and avoiding transmission collision, but doing so would significantly reduce the bandwidth efficiency. One way to tackle this issue is to use wireless network coding, in which different messages are smartly combined at cooperating devices to save the channel use for data relaying. Network coding has been widely used in wireline networks, but only until very recently was grafted onto the wireless networks. In the research community, it has been unknown for a long time whether network-coded cooperation is able to achieve the same diversity gain as the conventional diversity technique. On the industry side, how to efficiently apply network coding in the current wireless systems has also been an open design problem in the past few years. This thesis work aims to address these important issues and challenges and provide some theoretical guidelines for real system design. In the first part of this work, we study the fundamental diversity performance of uncoded cooperation systems with wireless network coding. It is demonstrated that network-coded cooperation generally cannot achieve the same diversity gain as the conventional diversity schemes; however, the diversity loss is usually very limited and occurs only under particular channel conditions. For example, for digital network coding we show that the error propagation issue would cause half of the total available diversity gain to be lost, and we develop several link adaptive schemes to mitigate the diversity loss. For analog network coding, we demonstrate that the associated co-channel interference may reduce the diversity as well, but such loss gradually diminishes as the transmitted power goes up. Finally for non-coherent network coding, we show that when the receivers do not know the channel state information, using blind signal detection would not hurt the dominant diversity gain, and the diversity loss occurs only at modest signal-to-noise ratio. The second part of this work is focused on coded cooperation systems. The unique feature of coded systems is that the devices could somehow know the network dynamics such as the decoding status of a transmitted packet. We explore two transmission strategies that could efficiently exploit such information. For two-way relay channel, we propose a network-coded retransmission strategy, where wireless relaying is employed only when the direct link is in outage. To reduce the number of retransmissions, network coding is performed in a static or dynamic way to combine the to-be-retransmitted packets intended for different end terminals. We analyze the throughput and develop power allocation scheme to maximize the throughput. We also develop a hybrid network coding scheme that can fully exploit the network coding gain in the multi-relay environment. Next for wireless uplink channel, we come up with multi-user cooperation scheme based on node clustering. We develop inter-cluster cooperation strategy and intra-cluster transmit beamforming scheme to exploit the cooperative diversity gain. We demonstrate that there is a basic tradeoff between diversity gain and bandwidth efficiency, and different tradeoffs could be achieved by changing the formation of the clusters.