EXTREMAL AND FINITENESS PROBLEMS IN RIEMANNIAN GEOMETRY : A SKETCH

GROVE, KARSTEN TOPOLOGY AND GEOMETRY RESEARCH CENTER 1994 Proceedings of the Topology and Geometry Research Vol.5 No.-

Common Parasites in Australasia

Grove, David I. Medical Publications Korea 1990 Medical Progress Vol.12 No.5

Ultrasonic characterization of exhumed cast iron water pipes

Groves, Paul,Cascante, Giovanni,Knight, Mark Techno-Press 2011 Smart Structures and Systems, An International Jou Vol.7 No.4

Cast iron pipe has been used as a water distribution technology in North America since the early nineteenth century. The first cast iron pipes were made of grey cast iron which was succeeded by ductile iron as a pipe material in the 1940s. These different iron alloys have significantly different microstructures which give rise to distinct mechanical properties. Insight into the non-destructive structural condition assessment of aging pipes can be advantageous in developing mitigation strategies for pipe failures. This paper examines the relationship between the small-strain and large-strain properties of exhumed cast iron water pipes. Nondestructive and destructive testing programs were performed on eight pipes varying in age from 40 to 130 years. The experimental program included microstructure evaluation and ultrasonic, tensile, and flexural testing. New applications of frequency domain analysis techniques including Fourier and wavelet transforms of ultrasonic pulse velocity measurements are presented. A low correlation between wave propagation and large-strain measurements was observed. However, the wave velocities were consistently different between ductile and grey cast iron pipes (14% to 18% difference); the ductile iron pipes showed the smaller variation in wave velocities. Thus, the variation of elastic properties for ductile iron was not enough to define a linear correlation because all the measurements were practically concentrated in single cluster of points. The cross-sectional areas of the specimens tested varied as a result of minor manufacturing defects and levels of corrosion. These variations affect the large strain testing results; but, surface defects have limited effect on wave velocities and may also contribute to the low correlations observed. Lamb waves are typically not considered in the evaluation of ultrasonic pulse velocity. However, Lamb waves were found to contribute significantly to the frequency content of the ultrasonic signals possibly resulting in the poor correlations observed. Therefore, correlations between wave velocities and large strain properties obtained using specimens manufactured in the laboratory must be used with caution in the condition assessment of aged water pipes especially for grey cast iron pipes.

Public/Private partnerships in Providing Re-housing Opportunities for Those Affected by Residential Clearance Programmes in UK

Rick Groves 한국주택학회 2003 주택연구 Vol.11 No.1

Government Intervention and Performance of the Private Rented Sector in Britain

Richard Groves,Alan Murie 외1명 한국주택학회 1998 주택연구 Vol.6 No.2

Housing and Urban Regeneration Programmes in the United Kindom

Richard Groves,Christopher Watson 한국주택학회 2002 주택연구 Vol.10 No.1

Ultrasonic characterization of exhumed cast ironwater pipes

Paul Groves,Giovanni Cascante,Mark Knight 국제구조공학회 2011 Smart Structures and Systems, An International Jou Vol.7 No.4

Cast iron pipe has been used as a water distribution technology in North America since the early nineteenth century. The first cast iron pipes were made of grey cast iron which was succeeded by ductile iron as a pipe material in the 1940s. These different iron alloys have significantly different microstructures which give rise to distinct mechanical properties. Insight into the non-destructive structural condition assessment of aging pipes can be advantageous in developing mitigation strategies for pipe failures. This paper examines the relationship between the small-strain and large-strain properties of exhumed cast iron water pipes. Nondestructive and destructive testing programs were performed on eight pipes varying in age from 40 to 130 years. The experimental program included microstructure evaluation and ultrasonic, tensile, and flexural testing. New applications of frequency domain analysis techniques including Fourier and wavelet transforms of ultrasonic pulse velocity measurements are presented. A low correlation between wave propagation and large-strain measurements was observed. However, the wave velocities were consistently different between ductile and grey cast iron pipes (14% to 18% difference); the ductile iron pipes showed the smaller variation in wave velocities. Thus, the variation of elastic properties for ductile iron was not enough to define a linear correlation because all the measurements were practically concentrated in single cluster of points. The cross-sectional areas of the specimens tested varied as a result of minor manufacturing defects and levels of corrosion. These variations affect the large strain testing results; but, surface defects have limited effect on wave velocities and may also contribute to the low correlations observed. Lamb waves are typically not considered in the evaluation of ultrasonic pulse velocity. However, Lamb waves were found to contribute significantly to the frequency content of the ultrasonic signals possibly resulting in the poor correlations observed. Therefore, correlations between wave velocities and large strain properties obtained using specimens manufactured in the laboratory must be used with caution in the condition assessment of aged water pipes especially for grey cast iron pipes.

Cutting mechanism and surface integrity in milling of Ti-5553 processed by selective laser melting

Thilo Grove,Berend Denkena,Oliver Maiß,Alexander Krödel,Holger Schwab,Uta Kühn 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.10

Titanium alloys are of significant importance in several high performance applications such as aerospace components or medical implants. Advances in additive technologies lead to an increase of additively built workpieces, offering new possibilities regarding functional integration and lightweight structures. Several authors have shown that microstructural, mechanical and thermal material properties differ significantly from those of cast alloys. Although additively produced parts are near net-shape, most of them are machined after the building process, to achieve the requirements regarding surface finish and dimensional accuracy. Titanium is generally known as a hardto-cut material due to its thermo-mechanical properties. Although there is a profound knowledge about the machinability of conventionally cast and wrought titanium alloys, there is a lack of understanding regarding the machining of additively built titanium. In this paper, the machinability of an additively built Ti-5Al-5V-5Mo-3Cr alloy (Ti-5553) is analyzed regarding chip formation, cutting forces and tool wear. Three different generation methods, conventional wrought, selective laser melting and selective laser melting with in-process (insitu) heat treatment are investigated. It is shown that the machinability differs significantly compared to a conventional wrought alloy, which is linked to decreased contact length on the tool rake face and higher mechanical tool load (up to + 23 % force increase). Highest tool load is found for titanium alloy, which is built using selective laser melting and in-process heat treatment. Furthermore, the surface integrity after machining is analyzed regarding hardness, roughness and residual stresses. Hereby, high compressive residual stresses for additively built titanium with in-process heat treatment are obtained due to the higher mechanical tool load. Therefore, it could be shown that the generation method (e.g. selective laser melting) needs to be considered for the later process design in finish machining.

Identification of a novel tRNA wobble uridine modifying activity in the biosynthesis of 5-methoxyuridine

Ryu, Huijeong,Grove, Tyler L,Almo, Steven C,Kim, Jungwook Oxford University Press 2018 Nucleic acids research Vol.46 No.17

<P><B>Abstract</B></P><P>Derivatives of 5-hydroxyuridine (ho<SUP>5</SUP>U), such as 5-methoxyuridine (mo<SUP>5</SUP>U) and 5-oxyacetyluridine (cmo<SUP>5</SUP>U), are ubiquitous modifications of the wobble position of bacterial tRNA that are believed to enhance translational fidelity by the ribosome. In gram-negative bacteria, the last step in the biosynthesis of cmo<SUP>5</SUP>U from ho<SUP>5</SUP>U involves the unique metabolite carboxy <I>S</I>-adenosylmethionine (Cx-SAM) and the carboxymethyl transferase CmoB. However, the equivalent position in the tRNA of Gram-positive bacteria is instead mo<SUP>5</SUP>U, where the methyl group is derived from SAM and installed by an unknown methyltransferase. By utilizing a <I>cmoB-</I>deficient strain of <I>Escherichia coli</I> as a host and assaying for the formation of mo<SUP>5</SUP>U in total RNA isolates with methyltransferases of unknown function from <I>Bacillus subtilis</I>, we found that this modification is installed by the enzyme TrmR (formerly known as YrrM). Furthermore, X-ray crystal structures of TrmR with and without the anticodon stemloop of tRNA<SUP>Ala</SUP> have been determined, which provide insight into both sequence and structure specificity in the interactions of TrmR with tRNA.</P>

Shape Selective Oxygen Transfer to Olefins Catalyzed by Sterically Hindered Iron Porphyrins

Ahn, Kwang-Hyun,Groves, John T. Korean Chemical Society 1994 Bulletin of the Korean Chemical Society Vol.15 No.11

Epoxidation of olefins catalyzed by iron-tetraarylporphyrins were studied to see the shape selectivity in the competing reaction between cis-and trans- or internal and external olefins. Cis-olefins were more reactive than trans-olefins in the competing reaction between cis-and trans-olefins. Interestingly, in the epoxidation of $cis-{\beta}-methystyrene$ by ${\alpha}{\beta}{\alpha}{\beta}$ atropisomer of Fe(III)TNPPPCl and iodosylbenzene, 27% of total product was phenylacetone. The unusually large amount of phenylacetone may be produced by hydride rearrangement of carbocationic intermediate. Regioselectivity of the reaction was also studied by using the most sterically hindered Fe(III)TTPPPCl. In the epoxidation of limonene with Fe(III)TTPPPCl, the disubstituted double bond was more reactive than trisubstituted double bond. This is in contrast to the results obtained with other iron-tetraarylporphyrins. Similar trend was also observed in the competing reaction between mono-and di-substituted olefins.