Divergent Design of Mechanical Metamaterials Clan Deducted from Arc-serpentine Curve

The exotic properties of mechanical metamaterials are determined by their unit-cells' structure and spatial arrangement, in analogy with the atoms of conventional materials. Companioned with the mechanism of structural or cellular materials1–5, the ancient wisdom of origami6–11 and kirigami12–16 and the involvement of multiphysics interaction2,17,18 enrich the programable mechanical behaviors of metamaterials, including shape-morphing8,12,14,16,19, compliance4,5,8,17,20, texture2,18,21, and topology11,18,22−25. However, typical design strategies are mainly convergent, which transfers various structures into one family of metamaterials that are relatively incompatible with the others and do not fully bring combinatorial principles3,10,26 into play. Here, we report a divergent strategy that designs a clan of mechanical metamaterials with diverse properties derived from a symmetric curve consisting of serpentines and arcs. We derived this composite curve into planar and cubic unit-cells and modularized them by attaching magnetics. Moreover, stacking each of them yields two- and three-dimensional auxetic metamaterials, respectively. Assembling with both modules, we achieved three thick plate-like metamaterials separately with flexibility, in-plane buckling, and foldability. Furthermore, we demonstrated that the hybrid of paradox properties is possible by combining two of the above assembles. We anticipate that this divergent strategy paves the path of building a hierarchical library of diverse combinable mechanical metamaterials and making conventional convergent strategies more efficient to various requests. Main

Composite Curve Path following an Underactuated AUV

This paper addresses the problem of composite curve path following for an underactuated autonomous underwater vehicle by utilizing an adaptive integral line-of-sight (AILOS) guidance and nonlinear iterative sliding mode (NISM) controller. First, the composite curve path is parametrized by a common scalar variable in a continuous way. Then, the kinematics error of an underactuated vehicle is described based on the nonprojection Frenet–Serret frame with a virtual point, which can be eliminated by the virtual point control and AILOS guidance. Meanwhile, the subpath switching algorithm is studied to realize the global path following for the composite curve path. Besides, the NISM controller is cascaded with the AILOS guidance law, and the cascade structure proved to be globally κ -exponentially stable under the influence of slow time-varying currents. Finally, simulations are considered to demonstrate the effectiveness of the proposed composite curve path following control scheme.

Integration of Low-Grade Heat from Exhaust Gases into Energy System of the Enterprise

In the paper is presented the way of Process Integration application for waste heat utilisation from exhaust gases streams with partial condensation. It is based on the construction of Hot Composite Curve representing the gaseous mixture cooling with accounting for the gas-liquid equilibrium of condensable vapour part. With Cold Composite Curve for streams requiring heating, the Pinch Point is determined. Then the structure of Heat Exchanger Network (HEN) for utilised Heat Integration into the energy system of the factory is developed accounting for the possible splitting of two-phase flow on gas and liquid streams and selection of plate heat exchanger (PHE) types for specific positions in HEN. The method is illustrated by a case study of heat utilisation from exhaust gases after superheated steam tobacco drying and flue gases from natural gas-fired boiler. The heat transfer areas of PHEs in HEN are optimised with the total annualised cost as an objective function. The payback period of the received solution is less than four months with a substantial saving of energy, reduction of greenhouse gases and other harmful emissions of combustion processes.

Heat Pump Bridge Analysis Using the Modified Energy Transfer Diagram

Heat pumps are the key technology to decarbonise thermal processes by upgrading industrial surplus heat using renewable electricity. Existing insight-based integration methods refer to the idealised Grand Composite Curve requiring the full exploitation of heat recovery potential but leave the question of how to deal with technical or economic limitations unanswered. In this work, a novel Heat Pump Bridge Analysis (HPBA) is introduced for practically targeting technical and economic heat pump potential by applying Coefficient of Performance curves into the Modified Energy Transfer Diagram (METD). Removing cross-Pinch violations and operating heat exchangers at minimum approach temperatures by combined application of Bridge Analysis increases the heat recovery rate and reduce the temperature lift to be pumped at the same time. The insight-based METD allows the individual matching of heat surpluses and deficits of individual streams with the capabilities and performance of different market-available heat pump concepts. For an illustrative example, the presented modifications based on HPBA increase the economically viable share of the technical heat pump potential from 61% to 79%.

ESTIMATION OF ANNUAL RUNOFF AND PEAK FLOW AT NAZANIN CATCHMENT IN ERBIL, KURDISTAN REGION USING DIFFERENT APPROACHES

Runoff is excess rainfall or a portion of rainfall that flows over the watershed. In un-gauged streams, due to lack of data, many methods are used for runoff estimation. In this paper annual runoff and peak flow of Nazanin watershed were estimated at Nazanin Dam location using different methods. Soil Conservation Service (SCS) method, basin relation, (Hydrologic Engineering Center – Hydrologic Modeling System) HEC-HMS and Hydrologic engineering center (HEC-1) models were provided. The Watershed Modeling System (WMS) package was used for watershed delineation and computation of curve number. The area of Nazanin catchment is 72.14 km2, and the composite curve number is 81.3. The results of average annual rainfall estimated using the basin relationship method are more than that obtained from SCS method. The results of peak flood discharge for different return periods using different approaches such as SCS method, HEC-HMS and HEC-1 models are very close. But the results of basin relation are lower than SCS method. From the results of comparison, it was observed that HEC-HMS and HEC-1 models can be used for generation flood hydrograph at ungagged watershed.

Investigating the Potential for Increased Energy Utilisation and Reduced CO2 Emissions at Mo Industrial Park

The potential for increased energy utilisation and reduced carbon footprint has been investigated for the industrial park Mo Industri Park (MIP), located at Mo i Rana, Norway. Process data has been gathered to quantify the energy flows between industrial clients. The energy flows have been visualised quantitatively in Sankey diagrams, while the quality of the available energy is presented in the form of a grand composite curve. High temperature flue gas from ferrosilicon (FeSi) production at Elkem Rana represent the largest heat source available for utilisation. A theoretical assessment of potential applications for this energy is presented and includes: (1) electricity production; (2) local biocarbon production, where surplus heat is utilised for drying of wood chips; (3) post combustion carbon capture, where surplus heat is utilised for solvent regeneration. The results indicate that increasing the current energy recovery from 400 GWh to >640 GWh is realistic. The increase in energy recovery can be used for reducing the carbon footprint of the industrial park. Investment in a common utility network for surplus heat may lower the threshold for establishing other energy clients at MIP. These are possibilities which may be investigated in more detail in future work.

Thermal Performance of Ammonia in Dual Mixed Refrigerant Cycle of Natural Gas Liquefaction Process

Mixed refrigerant (MR) system is commonly used for a liquefaction process of liquid natural gas (LNG) plants due to its higher efficiency of heat transfer rate compared to pure refrigerants. The performance of MR system is highly dependent on the variable refrigerant composition, which is challenging to obtain in a practical LNG plant setting. To address this challenge, this study investigates a unique approach to improve the exergy efficiency of liquefaction cycle employing ammonia in the mixture while keeping the MR molar composition constant in dual mixed refrigerant (DMR) cycle. A control strategy is proposed to regulate the MR flowrate through flow control sensors and a series of Joule-Thomason (JT) valves to sustain the desired efficiency of the cycle under various plant’s operation conditions. The robustness and adaptability of two proposed MR compositions were examined under eight cases by varying natural gas (NG) feed pressure and methane concentration. Composite curve plots were utilized as a tool to control the minimum temperature approach (MTA) and to improve exergy efficiency of the cycle. Furthermore, findings revealed that mixtures which included ammonia yielded a reduction in the number of compressors, as well as a reduced the overall amount of compressors rate of shaft work required for the liquefaction cycle. The results emphasize that DMR is most efficient when NG methane concentration is at 75%. Furthermore, the compressor rate of shaft work reduced by 13.3%, while exergy efficiency of the cycle increased by 14.3%, when natural gas methane concentration reduced from 90% to 75%.