Technology and Policy: System Acquisition in a Complex Operational Environment

The United States’ (US) ability to maintain a technological edge in the current operational environment is challenged by the increased ability of near-peer nations to produce military technology. In response to this problem, the US Army Engineer Research and Development Center (ERDC) seeks to model the three key elements of military system acquisition—context, product, and process—to develop a more comprehensive understanding regarding how and why nations acquire technical solutions. Through the application of the System Dynamics Modeling Process (SDMP), this research examines the interactions between the strategic context of Germany, the military products it acquires to address its operational needs, and the processes it employs to acquire military technology. The results of this research indicate that numerous dynamic variables of context impact the acquisitions process for Germany, particularly political support and subsequent monetary allocations to research and development.

Dynamic Modeling and Experimental Validation of a Water Hydraulic Soft Manipulator Based on an Improved Newton—Euler Iterative Method

Compared with rigid robots, soft robots have better adaptability to the environment because of their pliability. However, due to the lower structural stiffness of the soft manipulator, the posture of the manipulator is usually decided by the weight and the external load under operating conditions. Therefore, it is necessary to conduct dynamics modeling and movement analysis of the soft manipulator. In this paper, a fabric reinforced soft manipulator driven by a water hydraulic system is firstly proposed, and the dynamics of both the soft manipulator and hydraulic system are considered. Specifically, a dynamic model of the soft manipulator is established based on an improved Newton–Euler iterative method, which comprehensively considers the influence of inertial force, elastic force, damping force, as well as combined bending and torsion moments. The dynamics of the water hydraulic system consider the effects of cylinder inertia, friction, and water response. Finally, the accuracy of the proposed dynamic model is verified by comparing the simulation results with the experimental data about the steady and dynamic characteristics of the soft manipulator under various conditions. The results show that the maximum sectional error is about 0.0245 m and that the maximum cumulative error is 0.042 m, which validate the effectiveness of the proposed model.

Identifying stakeholders’ perspectives on the success factors of halal tourism in the city of Makassar: a group model building approach

Purpose Islamic attributes and activities need to be developed in compliance with the halal concept to attract potential Muslim tourists and ensure the success of halal tourism. Although the literature shows that many factors can influence the success of halal tourism, a complete picture of the success factors of halal tourism in a city is still very limited. As such, this explorative study aims to examine stakeholders’ perspectives regarding the antecedents of halal tourism success and the benefits of halal tourism for the city. Design/methodology/approach Qualitative system dynamics modeling was used for this study, and Makassar (a successful halal tourism city) was considered as the basis for the study. A causal loop diagram (CLD) of halal tourism was developed using the group model building technique to elicit stakeholders’ knowledge and assumptions. Network analysis and feedback loop analysis were used to identify the driving factors of successful halal tourism. Findings Two factors need to be taken into account by halal tourism stakeholders in the city: support from the central and local government and improving and maintaining potential tourists’ perceptions of the city. There are four benefits of halal tourism success for the city: an increase in the number of micro-, small- and medium-sized halal businesses in the city, increased support from the central and local government to further develop halal tourism infrastructure in the city, increased word-of-mouth promotion of Makassar as a tourism destination and a decrease in the price of halal tourism components (e.g. food and accommodation). Originality/value The resulting CLD shows the interlinkage between political, societal and economical factors that could influence the success of halal tourism development. In particular, the findings show how governments and tourism stakeholders need to promote halal tourism socialization in the community and improve the public perception of this type of tourism. Therefore, the findings can help destination stakeholders and tourism developers in other cities develop halal tourism potential.

Modeling and Simulation of Consumer Preference Decision for Commercial Complex Location Based on System Dynamics

The influencing factors of consumer shopping behavior play a key role in the later performance of commercial real estate enterprises. On the basis of analyzing the influence factors of customer patronage and the influence factors of commercial complex site selection decision and their relationship, a causal relationship graph and a system dynamic model are established, which can describe the influence of customer preference on commercial complex site selection decision. And introducing customer subjective factors optimize the original pure objective factors site selection decision model. The model is implemented by using the system dynamics modeling tool Vensim. At the same time, the model is verified by using the data of the first-hand investigation. The results show that the calculated data of the model is in good agreement with the actual data. The results show that the system dynamics method can effectively simulate the influence of various factors on the decision-making of the commercial complex. As the forecast of the model, the key indexes of the decision-making of the city commercial complex are discussed, and the measures to be taken are put forward, which can provide reference for the decision-making of the location.

Molecular dynamics modeling and simulation of water desalination through a double-walled carbon nanotube with moiré pattern

Freshwater scarcity has emerged as a major challenge of our time. Under this context, the importance of an efficient and energy-saving water desalination method is highlighted. In recent years, carbon nanotube (CNT) membrane characterizing with high permeability has attracted much attention in research, and it is regarded as a promising alternative to the conventional reverse osmosis technology. This work aims at numerically investigating the water desalination ability of a novel type of CNT membrane structure, namely the double-walled carbon nanotube (DWCNT) with Moiré pattern. After establishing the physical CNT models and running the molecular dynamics (MD) simulation of the water desalination system, it is found that both the single-walled carbon nanotube (SWCNT) and DWCNT can desalinate the seawater successfully while the water permeability of DWCNT is at least 18.9% higher than that of SWCNT within the same time. As far as the Moiŕe pattern adopted in this study is concerned, the water permeability of DWCNT without Moiŕe pattern is 18.6% higher than that with Moiré pattern.

Lower limb exoskeleton robots’ dynamics parameters identification based on improved beetle swarm optimization algorithm

Efficient and high-precision identification of dynamic parameters is the basis of model-based robot control. Firstly, this paper designed the structure and control system of the developed lower extremity exoskeleton robot. The dynamics modeling of the exoskeleton robot is performed. The minimum parameter set of the identified parameters is determined. The dynamic model is linearized based on the parallel axis theory. Based on the beetle antennae search algorithm (BAS) and particle swarm optimization (PSO), the beetle swarm optimization algorithm (BSO) was designed and applied to the identification of dynamic parameters. The update rule of each particle originates from BAS, and there is an individual’s judgment on the environment space in each iteration. This method does not rely on the historical best solution in the PSO and the current global optimal solution of the individual particle, thereby reducing the number of iterations and improving the search speed and accuracy. Four groups of test functions with different characteristics were used to verify the performance of the proposed algorithm. Experimental results show that the BSO algorithm has a good balance between exploration and exploitation capabilities to promote the beetle to move to the global optimum. Besides, the test was carried out on the exoskeleton dynamics model. This method can obtain independent dynamic parameters and achieve ideal identification accuracy. The prediction result of torque based on the identification method is in good agreement with the ideal torque of the robot control.

Surface elevation and ice thickness data between 2012 and 2020 at the ablation area of Artesonraju Glacier, Cordillera Blanca, Perú

We present a representative set of data of interpreted ice thickness and ice surface elevation of the ablation area of the Artesonraju glacier between 2012 and 2020. The ice thickness was obtained by means of Ground Penetrating Radar (GPR), while the surface elevation was by means of automated total stations and mass balance stakes. The results from GPR data show a maximum depth of 235 ± 18 m and a decreasing mean depth ranging from 134 ± 18 m in 2013 to 110 ± 18 m in 2020. Additionally, we estimate a mean ice thickness change rate of −4.2 ± 3.2 m yr−1 between 2014 and 2020 with GPR data alone, which is in agreement with the elevation change in the same period. The latter was estimated with the more accurate surface elevation data, yielding a change rate of −3.2 ± 0.2 m yr−1, and hence, confirming a negative glacier mass balance. The data set can be valuable for further analysis when combined with other data types, and as input for glacier dynamics modeling, ice volume estimations, and GLOF (glacial lake outburst flood) risk assessment. The complete dataset is available at https://doi.org/10.5281/zenodo.5571081 (Oberreuter et al, 2021).