Synthesis of Hybrid Flexible Mechanisms Using Beams and Spatial Design Constraints

Small scale turbomachines in domestic heat pumps reach high efficiency and provide oil-free solutions which improve heat-exchanger performance and offer major advantages in the design of advanced thermodynamic cycles. An appropriate turbocompressor for domestic air based heat pumps requires the ability to operate on a wide range of inlet pressure, pressure ratios and mass flows, confronting the designer with the necessity to compromise between range and efficiency. Further the design of small-scale direct driven turbomachines is a complex and interdisciplinary task. Textbook design procedures propose to split such systems into subcomponents and to design and optimize each element individually. This common procedure, however, tends to neglect the interactions between the different components leading to suboptimal solutions. The authors propose an approach based on the integrated philosophy for designing and optimizing gas bearing supported, direct driven turbocompressors for applications with challenging requirements with regards to operation range and efficiency. Using previously validated reduced order models for the different components an integrated model of the compressor is implemented and the optimum system found via multi-objective optimization. It is shown that compared to standard design procedure the integrated approach yields an increase of the seasonal compressor efficiency of more than 12 points. Further a design optimization based sensitivity analysis allows to investigate the influence of design constraints determined prior to optimization such as impeller surface roughness, rotor material and impeller force. A relaxation of these constrains yields additional room for improvement. Reduced impeller force improves efficiency due to a smaller thrust bearing mainly, whereas a lighter rotor material improves rotordynamic performance. A hydraulically smoother impeller surface improves the overall efficiency considerably by reducing aerodynamic losses. A combination of the relaxation of the 3 design constraints yields an additional improvement of 6 points compared to the original optimization process. The integrated design and optimization procedure implemented in the case of a complex design problem thus clearly shows its advantages compared to traditional design methods by allowing a truly exhaustive search for optimum solutions throughout the complete design space. It can be used for both design optimization and for design analysis.

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Mechanical Properties of Graphene Oxide Coupled by Multi-Physical Field: Grain Boundaries and Functional Groups

Crystals ◽

10.3390/cryst11010062 ◽

2021 ◽

Vol 11 (1) ◽

pp. 62

Author(s):

Xu Xu ◽

Zeping Zhang ◽

Wenjuan Yao

Keyword(s):

Mechanical Properties ◽

Graphene Oxide ◽

Grain Boundaries ◽

Functional Groups ◽

Oxygen Content ◽

Tensile Fracture ◽

Hydroxyl Groups ◽

Molecular Configuration ◽

Spatial Design ◽

Out Of Plane

Graphene and graphene oxide (GO) usually have grain boundaries (GBs) in the process of synthesis and preparation. Here, we “attach” GBs into GO, a new molecular configuration i.e., polycrystalline graphene oxide (PGO) is proposed. This paper aims to provide an insight into the stability and mechanical properties of PGO by using the molecular dynamics method. For this purpose, the “bottom-up” multi-structure-spatial design performance of PGO and the physical mechanism associated with the spatial structure in mixed dimensions (combination of sp2 and sp3) were studied. Also, the effect of defect coupling (GBs and functional groups) on the mechanical properties was revealed. Our results demonstrate that the existence of the GBs reduces the mechanical properties of PGO and show an “induction” role during the tensile fracture process. The presence of functional groups converts in-plane sp2 carbon atoms into out-of-plane sp3 hybrid carbons, causing uneven stress distribution. Moreover, the mechanical characteristics of PGO are very sensitive to the oxygen content of functional groups, which decrease with the increase of oxygen content. The weakening degree of epoxy groups is slightly greater than that of hydroxyl groups. Finally, we find that the mechanical properties of PGO will fall to the lowest values due to the defect coupling amplification mechanism when the functional groups are distributed at GBs.

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On the Spatial Design of Co-Fed Amines for Selective Dehydration of Methyl Lactate to Acrylates

ACS Catalysis ◽

10.1021/acscatal.1c00573 ◽

2021 ◽

pp. 5718-5735

Author(s):

Yutong Pang ◽

M. Alexander Ardagh ◽

Manish Shetty ◽

Anargyros Chatzidimitriou ◽

Gaurav Kumar ◽

...

Keyword(s):

Methyl Lactate ◽

Spatial Design

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Norfolk’s “Model Prison Community”: Howard Belding Gill and the Social Process of Prison Reform

The Prison Journal ◽

10.1177/0032885521991074 ◽

2021 ◽

Vol 101 (2) ◽

pp. 127-146

Author(s):

Matthew DelSesto

Keyword(s):

Criminal Justice ◽

Social Process ◽

Prison Reform ◽

Criminal Justice Reform ◽

Spatial Design ◽

The Social ◽

Public Consciousness ◽

Prison Community ◽

The Relationship

This article explores the social process of criminal justice reform, from Howard Belding Gill’s 1927 appointment as the first superintendent of the Norfolk Prison Colony to his dramatic State House hearing and dismissal in 1934. In order to understand the social and spatial design of Norfolk’s “model prison community,” this article reviews Gills’ tenure as superintendent through administrative documents, newspaper reports, and his writings on criminal justice reform. Particular attention is given to the relationship between correctional administration and public consciousness. Concluding insights are offered on the possible lessons from Norfolk Prison Colony for contemporary reform efforts.

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