In this paper, we present a CAD-oriented and feature-driven topology optimization methodology for engineering structures with freeform design domains. Mixed solid–void features are adopted as basic ...design primitives to build a unified formulation of feature definition, while pure solid or pure void features are considered as two special cases. Topology optimization is achieved as a Boolean intersection process between the so-called topology variation modeler (TVM) and freeform design domain modeler (FDDM) in terms of level-set functions (LSFs). The TVMs constructed with solid and/or void features are applied to clip the FDDM through Boolean operations. It is shown that sensitivity analysis with boundary integral scheme is independent of the mathematical expressions of the LSF. Numerical problems with freeform and periodic design domains are dealt with to demonstrate the proposed topology optimization method.
•Design and dynamic models are developed for PCHEs in sCO2 Brayton cycles.•Models are validated with the laboratory operating data.•Design guidance is provided for a 10 MWe pilot-scale sCO2 Brayton ...cycle.•Key design and dynamic measures of three types of exchangers are compared.
Due to the unique geometries and hydraulics of printed circuit heat exchangers and rapidly changing properties of supercritical carbon dioxide, the effective design and rating of printed circuit heat exchangers is an essential requirement for their use in supercritical carbon dioxide power cycles. In this study, one-dimensional design and dynamic models have been developed in Aspen Custom Modeler for printed circuit heat exchangers utilized in printed circuit heat exchangers Brayton power cycles. The design model is used to determine the optimal geometry parameters by minimizing the metal mass. The dynamic model is used to predict transient behavior and can be easily implemented into system-level models developed in Aspen Plus Dynamics for cycle performance evaluations. In these models, the heat transfer coefficient and friction factor are calculated using data reported by Heatric, a prominent printed circuit heat exchanger manufacturer. Both models are validated by comparing with the data from a small-scale exchanger used in the 100 kWe facility operated by the Naval Nuclear Laboratory, and then applied to design and simulate low- and high-temperature recuperators for a 10 MWe supercritical carbon dioxide indirect recompression closed Brayton cycle, which is of interest to the U.S. Department of Energy. The designs and dynamic responses of the printed circuit heat exchangers are compared with conventional shell-and-tube exchangers and microtube shell-and-tube exchangers for the same applications. The simulation results indicate that the proposed printed circuit heat exchangers have fast dynamic responses due to their small metal masses and high heat transfer coefficients compared with the conventional shell-and-tube exchangers. Even though the metal masses of the designed PCHEs are slightly higher than those of the microtube shell-and-tube exchangers, the printed circuit heat exchangers are still promising candidates for heat recuperation because of their mature manufacturing procedures and abundant laboratory and industrial operating experience.
This paper aims at dealing with realistic and challenging design problems of stress constrained topology optimization with free-form design domains. First, the concept of level set function (LSF) ...based modelers is introduced to transform this kind of problems into the Boolean conjunction operation of a topology variation modeler (TVM) onto a free-form design domain modeler (FDDM). Such an operation is mathematically realized by means of the so-called R-functions in the form of implicit LSFs. Within this framework, topology optimization problems are classified into two general cases depending upon the existence of non-designable solid feature. Analytical sensitivity analysis formulas are further derived. Compared with the existing level set based method, the important sensitivity property of design domain preserving makes it possible to avoid automatically the boundary violation of the design domain caused by the zero level set movement and both the topology and boundary shape of the free-form design domain can be simultaneously optimized. Second, the implementation of the finite cell method (FCM) ensures the stress computing accuracy in the fixed mesh due to the use of high-order shape functions and adaptive integration scheme. The combination of the active-set strategy and the dynamic aggregation technique also reduces the number of local stress constraints greatly. Finally, representative examples are presented to illustrate the conveniences and effectiveness of the proposed method.
Abstrak
Kelurahan Oesapa Barat merupakan Kelurahan di Kecamatan Kelapa Lima Kota Kupang Indonesia yang memiliki hutan mangrove cukup luas namun terus mengalami kerusakan yang disebabkan oleh ulah ...manusia, sehingga upaya untuk menahan laju kepunahan hutan mangrove perlu dilakukan. Dalam upaya pengelolaan untuk menahan laju kepunahan hutan mangrove, diperlukan informasi berupa identifikasii area mana saja yang membutuhkan perhatian untuk pelestarian mangrove. Oleh sebab itu, dibutuhkan suatu metode yang dapat digunakan untuk monitoring perubahan luasan mangrove dari tahun ke tahun. Gambaran perubahan lahan di masa depanpun dibutuhkan untuk mendukung perencanaan, perlindungan, dan rehabilitasi hutan mangrove. Tujuan penelitian ini adalah mengetahui perubahan tutupan mangrove tahun 1996, 2006, 2016, dan memprediksi tutupan mangrove tahun 2026. Teknologi penginderaan jauh digunakan untuk menganalis penggunaan lahan melalui citra satelit Landsat (tahun 1996, 2006 dan 2016). Penelitian ini menggunakan integrasi citra landsat untuk memperoleh hasil klasifikasi tutupan lahan dan land change modeler untuk mengkaji dan memprediksi pola perubahan lahan mangrove. Hasil prediksi hutan mangrove menggunakan land change modeler menunjukan adanya tren peningkatan luasan mangrove sebesar 17,64 ha pada tahun 1996, 18,90 ha pada tahun 2006, 19,80 ha pada tahun 2016, dan 20,52 ha pada tahun 2026. Peningkatan luasan mangrove disebabkan oleh berhasilnya kegiatan rehabilitasi berupa penanaman mangrove di Pantai Kelurahan Oesapa Barat pada tahun 2002.
Abstract
Oesapa Barat Village is a sub-district in Kelapa Lima District, Kupang City, Indonesia where has a large mangrove forest but continues to decline by human activities, therefore the protection of mangroves is urgent. The purpose of this study was to determine mangroves' changes in 1996, 2006, 2016, and predict them in 2026. Remote sensing technology was used to analyze land use through Landsat satellite imagery (1996, 2006, and 2016). This research uses the integration of Landsat image to obtain land cover classification and land change modeler to analyze and predict mangrove land change patterns. The prediction results using land change modeler showed that there was a trend of increasing mangrove area by 17.64 ha in 1996, 18.90 ha in 2006, 19.80 ha in 2016, and 20.52 ha in 2026. The increase in mangrove areas was caused by the success of this activity. rehabilitation in the form of planting mangroves in West Oesapa Village Beach in 2002.
Social economy of China has been rapidly developing for more than 30years with efficient reforms and policies being issued. Societal developments have resulted in a greater use of many natural ...resources to the extent that the ecosystem can no longer self-regulate, thus severely damaging the balance of the ecosystem itself. This in turn has led to a deterioration in people's living environments. Our research is based on a combination of climate scenarios presented in the fifth report of the Intergovernmental Panel on Climate Change (IPCC) and policy scenarios, including the one-child policy and carbon tax policy. We adopted Land Change Modeler of IDRISI software to simulate and analyze land-use change under 16 future scenarios in 2050. Carbon sequestration, soil conservation and water yields were quantified, based on those land-use maps and different ecosystem models. We also analyzed trade-offs and synergy among each ecosystem service and discussed why those interactions happened. The results show that: (1) Global climate change has a strong influence on future changes in land-use. (2) Carbon sequestration, water yield and soil conservation have a mutual relationship in the Guanzhong-Tianshui economic region. (3) Climate change and implementation of policy have a conspicuous impact on the changes in ecosystem services in the Guanzhong-Tianshui economic region. This paper can be used as a reference for further related research, and provide a reliable basis for achieving the sustainable development of the ecosystem.
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•Combinations of climate and policy scenarios.•Land-use of scenarios were obtained.•Interactions exist among ecosystem services.
This investigation was performed to obtain a promising phytase enzyme producing yeast. In this regard, the PSM was used to isolate the phytase-producing Hanseniaspora guilliermondii S1 (MG663578) ...from sugarcane juice. The SSF optimum conditions for phytase generation were optimized using (OVAT) one-variable-at-a-time strategy using both Box-Behnken design and shake flask method (g/100 ml: 0.05 yeast extract, 0.15 Peptone, 0.05 malt extract 0.50 dextrose, pH 5.8 and 28ᵒC). The protein model developed was shown to be adequate for phytase production (91% accuracy), with the greatest phytase productivity in shake flask with substrate jack fruit seed powder being 395 ± 0.43 U/ml compared to 365U/ml for the BBD projected value. Crude Phytase was partially purified with a protein recovery of 43%, revealing a molecular weight of 120 kDa. It had an enzyme kinetic value of Km 3.3 mM and a Vmax of 19.1 mol/min. The 3D structure of PhyS1 amino acid sequences (PhyS1. B99990002) was simulated using Modeler 9.23, and the validated result revealed that 86.7% were in the favored region by Ramachandran plot. The SAVES server verified the 3D PDB file as satisfactory, and the model (in.pdb format) was uploaded in the PMDB database with the accession number ID: PM0082974. At the lab level, Hanseniaspora guilliermondii S1 (MG663578) producing phytase exhibited successful plant growth promotion activity in Ragi - CO 19 (Eleusine coracana L.) and Rice -Navarai - IR 64 (Oryza sativa L.). As a result, a phytase-based formulation for sustainable agriculture must be developed and tested on a large scale in diverse geographical areas of agricultural lands to determine its effect and potential on plant development.
•SSF optimized via OVAT strategy and Box-Behnken design.•Protein model adequate for phytase production (91% accuracy).•Phytase productivity highest with jackfruit seed powder substrate.•Prediction of active sites and 3D model of Phytase from H. guilliermondii S1.•H. guilliermondii S1 (MG663578) phytase promotes Rice plant growth.
With the rapid development of modern cities, relatively backward traffic management methods, inadequate road planning and construction, and the surge in car ownership, the problem of “urban traffic ...congestion” has become a problem faced by modern urban management. Intelligent Transportation System (ITS) is gradually becoming the research direction for solving the problem of traffic congestion in various countries around the world. Based on the above background, the purpose of this article is to study the vehicle communication network in the intelligent transportation system based on the Internet of Things. This paper uses OPNET Modeler software to build a vehicle movement model. OPNET Modeler uses a layered network simulation method. From the perspective of the protocol, the node module complies with the OSI standard of the open system interconnection model. From bottom to top, it is the physical layer, MAC layer, ARP layer, IP encapsulation layer, IP layer, TCP layer, and service layer. In a multi-hop scenario of vehicle self-organizing network in an intelligent transportation system based on the Internet of Things, simulation experiments show that when the vehicle is running at low speed, the wireless network coverage problem of the vehicle self-organizing network on the ground, especially In terms of the design and configuration of the roadside unit, the distance of the roadside unit should be maintained between 500 m and 600 m. At this time, the overall performance of the vehicle self-organizing network is stable. AODV protocol is superior to DSR protocol in terms of throughput, average network delay, routing load, packet loss rate, and average routing hops, and is more suitable for network communication needs.
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•Performance of RPBs are studied for the first time for acid gas enrichment process.•Aspen Custom Modeler software was used for both design and simulation purposes.•The replaced RPBs ...reduced the total bed volume by 97%, from 235 m3 to 7.7058 m3.•The lean MDEA flow rate was also decreased from 6069 kmole/hr to 5100 kmole/hr.•A brilliant discussion is provided on sensitivity analysis of the entire process.
Conventional packed beds are traditionally used for acid gas enrichment processes. Rotating packed beds (RPBs) are unique, compact and effective technology, which can easily replace conventional packed beds for process intensification purposes. Two scenarios are used to substitute Khangiran natural gas refinery enrichment column with a couple of specially designed RPBs. The first scheme mirrors the exact existing process, while the second scenario provides an additional rich solvent stream directly delivered to amine regeneration unit. Aspen Custom Modeler software is employed to perform the entire simulations. As expected, replacing conventional packed bed with RPBs can drastically reduce the geometries of the packed beds and leads to considerable decrease in lean amine consumption. The second scenario performs more adequately and reduces the lean methyl-diethanolamine (MDEA) flow rate entering the enrichment section from 6069 kmole/hr to 5100 kmole/hr. The required enrichment equipment volume is also reduced from 235 m3 to 7.7 m3 (<3% of original value) and the packing volume collapses about 78 folds (from 59 m3 to 0.75 m3). A thorough discussion is also provided on sensitivity analysis of the entire enrichment process versus various input variables (i.e.: RPBs rotational speeds, their operating pressures and the lean amine rate entering enrichment tower). Finally, the results of cost estimation revealed that using the second more optimal RPB scenario reduced both operating costs and captital investments by 15.4% and 85.4%, respectively.
This work considers the use of a Molten Carbonate Fuel Cell (MCFC) system as a power generation and CO2 concentrator unit downstream of the coal burner of an existing production plant. In this way, ...the capability of MCFCs for CO2 segregation, which today is studied primarily in reference to large-scale plants, is applied to an intermediate-size plant highlighting the potential for MCFC use as a low energy method of carbon capture. A technical feasibility analysis was performed using an MCFC system-integrated model capable of determining steady-state performance across varying feed composition. The MCFC user model was implemented in Aspen Custom Modeler and integrated into the reference plant in Aspen Plus. The model considers electrochemical, thermal, and mass balance effects to simulate cell electrical and CO2 segregation performance. Results obtained suggest a specific energy requirement of 1.41 MJ kg CO2−1 significantly lower than seen in conventional Monoethanolamine (MEA) capture processes.
•An MCFC system has been tested for carbon capture downstream a coal burner.•A local balance model was used to specifically analyse the MCFC performance.•MCFC can improve the system efficiency compared to other solutions.
Critical watersheds that exceed their carrying capacity occur in many regions of the world; their formation is facilitated by a significant driving factor known as land use/land cover (LULC) changes. ...This study aims to identify the LULC changes in Cisadane Watershed, Indonesia, in 2010, 2015, 2021, and simulate future LULC for 2030 and 2050. Landsat 2010 and 2015 and Sentinel 2A images from 2020 were employed for deriving LULC maps using Random Forest. This study applied a Land change modeler (LCM) under the multi-layer perception Markov chain (MLP-MC) to predict the future LULC in three scenarios. The scenarios are business as usual (BAU), protecting paddy fields (PPF), and protecting forest areas (PFA). The results showed that all the LULC maps demonstrated excellent accuracy, indicated by >83% overall accuracy. Furthermore, BAU produces the worst effect of decreasing forest and paddy field areas. PPF tends to cause forest loss, while PFA is predicted to reduce the paddy fields. There is a trade-off between maintaining food security and conserving natural resources. The study reveals the importance of efficient land use planning in the future amidst increasing resource demand due to population growth while existing land resources are limited.
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