An investigation of hydraulic-line resonance and its attenuation

An investigation of fluid resonance in high-pressure hydraulic lines has been made with two types of fluid dampers (or filters) installed in the line. One type involved the use of one or more closed-end tubes branching at right angles from a main line, and the other type was a fluid muffler installed in-line. These devices were evaluated in forced vibration tests with oscillatory disturbances over a 1000-Hz range applied to one end of the line and with oscillatory pressures measured at various stations along the main pipe. Limited applications of acoustic-wave theory to the branched systems are also included. Results show varying attenuations of pressure perturbations, depending on the number and location of branches and the type of muffler. Up to three branches were used in the branch-resonator study, and the largest frequency range with maximum attenuation was obtained for a three-branch configuration. The widest frequency ranges with significant attenuations were obtained with two types of fluid mufflers

The nonlinear time-dependent response of isotactic polypropylene

Tensile creep tests, tensile relaxation tests and a tensile test with a constant rate of strain are performed on injection-molded isotactic polypropylene at room temperature in the vicinity of the yield point. A constitutive model is derived for the time-dependent behavior of semi-crystalline polymers. A polymer is treated as an equivalent network of chains bridged by permanent junctions. The network is modelled as an ensemble of passive meso-regions (with affine nodes) and active meso-domains (where junctions slip with respect to their positions in the bulk medium with various rates). The distribution of activation energies for sliding in active meso-regions is described by a random energy model. Adjustable parameters in the stress--strain relations are found by fitting experimental data. It is demonstrated that the concentration of active meso-domains monotonically grows with strain, whereas the average potential energy for sliding of junctions and the standard deviation of activation energies suffer substantial drops at the yield point. With reference to the concept of dual population of crystalline lamellae, these changes in material parameters are attributed to transition from breakage of subsidiary (thin) lamellae in the sub-yield region to fragmentation of primary (thick) lamellae in the post-yield region of deformation.Comment: 29 pages, 12 figure

Designing spin-spin interactions with one and two dimensional ion crystals in planar micro traps

We discuss the experimental feasibility of quantum simulation with trapped ion crystals, using magnetic field gradients. We describe a micro structured planar ion trap, which contains a central wire loop generating a strong magnetic gradient of about 20 T/m in an ion crystal held about 160 \mu m above the surface. On the theoretical side, we extend a proposal about spin-spin interactions via magnetic gradient induced coupling (MAGIC) [Johanning, et al, J. Phys. B: At. Mol. Opt. Phys. 42 (2009) 154009]. We describe aspects where planar ion traps promise novel physics: Spin-spin coupling strengths of transversal eigenmodes exhibit significant advantages over the coupling schemes in longitudinal direction that have been previously investigated. With a chip device and a magnetic field coil with small inductance, a resonant enhancement of magnetic spin forces through the application of alternating magnetic field gradients is proposed. Such resonantly enhanced spin-spin coupling may be used, for instance, to create Schr\"odinger cat states. Finally we investigate magnetic gradient interactions in two-dimensional ion crystals, and discuss frustration effects in such two-dimensional arrangements.Comment: 20 pages, 13 figure

Controllable motions of compressible simple materials of various types

It is shown that a motion is possible in every compressible homogeneous isotropic simple solid having a certain range of memory, in the presence of a constant body force field, if and only if it is homogeneous and uniformly accelerated after a certain time. In the class of solids having perfect memory, the only motion of this kind which can be smoothly initiated in a body at rest is a rigid one. For the class of solids having finite memory of duration T and initially at rest, the motions of the type considered need be homogeneous and uniformly accelerated only after time T . For those solids having fading memory, the motion must reduce to a fixed homogeneous deformation. Similar results are developed for simple fluids and anisotropic simple solids. Es wird gezeigt, daß in jedem kompressiblen, homogenen und isotropen einfachen Festkörper mit einem gewissen Erinnerungsbereich und in Gegenwart eines konstanten Massenkraftfeldes eine Bewegung dann und nur dann möglich ist, wenn sie homogen und nach einer gewissen Zeit gleichmäßig beschleunigt ist. Bei Festkörpern mit vollkommener Erinnerung ist die einzige Bewegung dieser Art, die bei einem ruhenden Körper glatt eingeleitet werden kann, eine starre. Bei Festkörpern mit begrenzter Erinnerungsdauer T , die anfangs in Ruhe waren, müssen die Bewegungen der betrachteten Art homogen und nur nach der Zeit T gleichmäßig beschleunigt sein. Für Festkörper mit schwindendem Gedächtnis reduziert sich die Bewegung auf eien feste homogene Verformung. Ähnliche Ergebnisse werden für einfache Flüssigkeiten und anisotrope einfache Festkörper entwickelt.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41721/1/707_2005_Article_BF01204714.pd

A model for nonlinear viscoelastic torsional response of an elastomeric bushing

An elastomeric bushing is a device used in automotive suspension systems to cushion the loads transmitted from the wheel to the frame of the vehicle. A bushing is essentially an elastomeric hollow cylinder which is bonded to a solid metal shaft at its inner surface and a metal sleeve at its outer surface. The shaft is connected to the suspension and the sleeve is connected to the frame. The elastomeric cylinder provides the cushion when it deforms due to relative motion between the shaft and the sleeve. The relation between the force or moment applied to the shaft or sleeve and the relative displacements or rotations is nonlinear and exhibits features of viscoelasticity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41703/1/707_2005_Article_BF01305752.pd

Workplace productivity and office type: an evaluation of office occupier differences based on age and gender

Purpose Open plan office environments are considered to offer workplace productivity benefits because of the opportunities that they create for interaction and knowledge exchange, but more recent research has highlighted noise, distraction and loss of privacy as significant productivity penalties with this office layout. This study aims to investigate if the purported productivity benefits of open plan outweigh the potential productivity penalties. Design/methodology/approach Previous research suggests that office environments are experienced differently according to the gender and age of the occupier across both open-plan and enclosed configurations. Empirical research undertaken with office occupiers in the Middle East (N=220) led to evaluations to establish the impact different offices had on perceived productivity. Factor analysis was used to establish five underlying components of office productivity. The five factors are subsequently used as the basis for comparison between office occupiers based on age, gender and office type. Findings This research shows that benefits and penalties to workplace productivity are experienced equally across open-plan and enclosed office environments. The greatest impact on perceived workplace productivity however was availability of a variety of physical layouts, control over interaction and the 'downtime' offered by social interaction points. Male occupiers and those from younger generations were also found to consider the office environment to have more of a negative impact on their perceived workplace productivity compared to female and older occupiers. Originality/value The originality of this paper is that it develops the concept of profiling office occupiers with the aim of better matching office provision. This paper aims to establish different occupier profiles based on age, gender and office type. Data analysis techniques such as factor analysis and t-test analysis identify the need for different spaces so that occupiers can choose the most appropriate space to best undertake a particular work task. In addition, it emphasises the value that occupiers place on ‘downtime’ leading to the need for appropriate social space

Active/Passive, ‘Diminished’/‘Beautiful’, ‘Light’ from Above and Below: Rereading Shekhinah’s Sexual Desire in Zohar al Shir ha-Shirim (Song of Songs)

In Zohar al Shir ha-Shirim, the Zohar’s reading of Song of Songs, Shekhinah, echoing themes associated with the Shulamite of the biblical text, consistently initiates cosmic union. Sexual desire in the zoharic texts is a form of capital necessary to facilitate sefirotic intercourse, although scholarly readings of the zoharic corpus often identify Shekhinah as a passive receptacle. This, however, is only true if the endemic contradictions within the texts are glossed over. In Song of Songs, the Shulamite’s sexual ‘initiative’ is core. This was not lost on the author(s) of Zohar al Shir ha-Shirim, who, in struggling to explain Shekhinah’s sefirotic role in line with the erotics of Song of Songs, inescapably echoed the ‘depatriarchalizing’ themes of the biblical text. As this article demonstrates, in Zohar al Shir ha-Shirim, Shekhinah is active and repeatedly encourages and frustrates cosmic sexual intercourse. Zohar al Shir ha-Shirim shows that it is possible to reread Shekhinah’s role beyond the androcentrism of the authors as well as scholarly assumptions about her passivity

The management aspect of psychotherapy with aggressive children

Psychotherapy with an aggressive child may require the imposition of rather firm limitations over aspects of the patient's aggressive behavior. The nature of this management strategy is determined by the individual child's psychopathology. The management aspects of the psychotherapy with two aggressive boys are illustrated in detail. In one case, stringent limitations were imposed when it was discovered that the boy's behavior was regressive and represented an effort to sadistically control people in his environment. In the other case, the behavior was initially left almost unchallenged; this boy's aggressive and delinquent behavior reflected an effort to achieve a sense of order in an inconsistent external and potentially chaotic internal environment.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43969/1/10578_2005_Article_BF01463450.pd

On general measures of deformation

Each particle of a continuum is assigned a second order tensor which is taken as a measure of the deformation of some neighborhood of the particle, and which is determined by a functional depending on the configurations of that neighborhood. Two invariance restrictions are imposed on the functional whose values are spatial strain tensors, that is, associated with the deformed configuration. The first requirement is that a time shift and rigid transformation of the deformed configuration leave the spatial deformation tensor unaltered relative to it. The second requires that if particles of distinct continua undergo the same deformation, the corresponding deformation tensors should be the same. For the special case in which the functional depends on the deformation in the smallest neighborhood of a particle, the restrictions imply that the deformation tensors associated with the deformed and reference configurations are isotropic functions of the left and right Cauchy-Green tensors, respectively. Jedem Teilchen eines Kontinuums wird ein Tensor zweiter Stufe als Maß für die Deformation einer gewissen Nachbarschaft dieses Teilchen zugeordnet, der durch ein Funktional bestimmt wird, das von der Konfiguration dieser Nachbarschaft abhängt. Zwei Invarianzbedingungen werden diesem Funktional, dessen Werte räumliche Verzerrungstensoren darstellen, auferlegt, und zwar im Hindblick auf die deformierte Konfiguration. Die erste Forderung besagt, daß eine Zeitverschiebung und eine starre Transformation der deformierten Konfiguration den räumlichen Verzerrungstensor im Hinblick auf diese ungeändert lassen. Die zweite Einschränkung besagt, daß entsprechende Deformationstensoren von Partikeln verschiedener Kontinua, die dieselbe Verformung erlitten haben, gleich sein sollen. Im Spezialfall, daß die Funktionale nur von der Deformation in der nächsten Umgebung des Partikels abhängen, beinhalten die Einschränkungen die Aussage, daß die mit dem deformierten und dem undeformierten Zustand verknüpften Deformationstensoren nur isotrope Funktionen des linken und des rechten Cauchy-Green Tensors sein können.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41717/1/707_2005_Article_BF01172146.pd

A constitutive representation for linear aging, environmental-dependent viscoelastic materials

This study is concerned with developing a constitutive law for aging and environmental-dependent materials. The development rests on the assumption that the mechanical properties of the aforementioned materials can be mathematically represented by a functional of the strain and environmental histories, and this functional depends on the present time and the time the material is created. This constitutive assumption leads to two equivalent integral forms of the constitutive law after asserting that the functional is linear in the strain history. The first form of the integral law contains a material response functional analogous to the creep and relaxation functions of classical linear viscoelasticity. The second integral law has the same basic mathematical form but the physical interpretation of the mechanical response functional is different. It is demonstrated that both forms of the aging law reduce to the same non-aging law which is the usual starting for an analysis of only environmental-dependent materials. In the Appendix an operator algebra is presented for convenience in manipulating the integral laws for aging materials. Diese Untersuchung beschäftigt sich mit der Darstellung eines Werkstoffgesetzes für Altern und für umgebungsabhängige Stoffe. Die Entwicklung beruht auf der Annahme, daß die mechanischen Eigenschaften der oben erwähnten Stoffe mathematisch durch ein Funktional der Verzerrungs- und der Umgebungsgeschichten dargestellt werden kann und daß dieses Funktional von der augenblicklichen Zeit und der Zeit der Erzeugung des Stoffes abhängt. Diese Werkstoffannahme führt, unter der Voraussetzung einer linearen Abhängigkeit des Funktionals von der Verzerrungsgeschichte, auf zwei äquivalente Integraldarstellungen des Werkstoffgesetzes. Die erste Darstellung des Integralgesetzes enthält ein Materialantwort-Funktional analog der Kriech- und Relaxationsfunktionen der klassischen linearen Viskoelastizität. Das zweite Gesetz hat die gleiche mathematische Gestalt, aber verschiedene physikalische Interpretation des mechanischen Antwort-Funktionals. Es wird gezeigt, daß für nicht-alternde Stoffe beide Darstellungen dasselbe Gesetz, das der übliche Ausgangspunkt einer Untersuchung umgebungsbeeinflußter Stoffe ist, ergeben. Im Anhang werden einige für das Rechnen mit den Integralgesetzen alternder Stoffe handliche Sätze der Operatorenrechnung angegeben.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41700/1/707_2005_Article_BF01179657.pd