Plane Split Research Articles

Laboratory and In Situ Simulation Tests of the Excavation Damaged Zone Around Galleries in Opalinus Clay

In the context of nuclear waste disposal in clay formations, laboratory and in situ simulation experiments were performed to study at reduced scale the excavation damaged zone (EDZ) around tunnels in the indurated Opalinus Clay at Mont Terri, Switzerland. In the laboratory, thick-walled hollow cylindrical specimens were subjected to a mechanical unloading mimicking a gallery excavation. In samples cored parallel to bedding, cracks sub-parallel to the bedding planes open and lead to a buckling failure in two regions that extend from the borehole in the direction normal to bedding. The behaviour is clearly anisotropic. On the other hand, in experiments performed on specimens cored perpendicular to bedding, there is no indication of failure around the hole and the response of the hollow cylinder sample is mainly isotropic. The in situ experiment at Mont Terri which consisted in the overcoring of a resin-injected borehole that follows the bedding strike of the Opalinus Clay showed a striking similarity between the induced damaged zone and the fracture pattern observed in the hollow cylinder tests on samples cored parallel to bedding and such a bedding controlled “Excavation” Damaged Zone is as well consistent with the distinct fracture patterns observed at Mont Terri depending on the orientation of holes/galleries with respect to the bedding planes. Interestingly, the damaged zone observed in the hollow cylinder tests on samples cored parallel to bedding and in situ around URL galleries is found to develop in reverse directions in Boom Clay (Mol) and in Opalinus Clay (Mont Terri). This most probably results from different failure mechanisms, i.e. shear failure along conjugated planes in the plastic Boom Clay, but bedding plane splitting and buckling in the indurated Opalinus Clay.

Stitching a Reference Plane Split Using Routing Layer Traces to Improve I/O Bus Signal Integrity

While on-board interconnects are operating at much higher frequencies, the cost of the overall computing system has been decreasing. Computer manufacturers are therefore continuously looking for ways to lower the production cost. In a mobile computing system, where size is a main constraint and expensive high layer count printed circuit board (PCB) technology has been used to control routing congestion, using cheaper technologies with a smaller number of routing layers is an attractive mean of controlling manufacturing cost. On the other hand, routing on a severely size-constrained mobile platform with a smaller number of routing layers can inadvertently expose wide high speed digital interfaces to non-ideal conditions such as reference plane gaps produced by various power and ground islands. Multi-GHz operation of these high speed signals also means that the traditional mitigation method of adding bypass capacitors across the reference gaps is becoming inefiective. In this paper, we propose to use stitching patch underneath the splitting power and ground plane that can be used in conjunction with bypass capacitors to mitigate the efiect of these reference plane gaps on signal quality, as well as system EMI and ESD. DOI: 10.2529/PIERS060908032425

Lameness in 46 horses associated with deep digital flexor tendonitis in the digit: diagnosis confirmed with magnetic resonance imaging.

The differential diagnosis of foot pain has long proved difficult and the use of magnetic resonance imaging (MRI) offers the opportunity to further the clinical understanding of the subject. To determine the incidence of deep digital flexor tendon (DDFT) injuries in a series of 75 horses with lameness associated with pain localised to the digit, with no significant detectable radiographic or ultrasonographic abnormalities, using MRI; and to describe a variety of lesion types and relate DDF tendonitis with anamnesis, clinical features, response to local analgesic techniques and nuclear scintigraphic and ultrasonographic findings. All horses undergoing MRI of the front feet between January 2001 and October 2002 were reviewed and those with DDFT injuries categorised according to lesion type; horses with primary tendonitis (Group I) and those with concurrent abnormalities of the navicular bone considered to be an important component of the lameness (Group II). The response to perineural analgesia of the palmar digital nerves and palmar (abaxial sesamoid) nerves, intra-articular analgesia of the distal interphalangeal (DIP) joint and analgesia of the navicular bursa were reviewed. The result of ultrasonography of the pastern and foot was recorded. Lateral, dorsal and solar pool and bone phase nuclear scintigraphic images were assessed subjectively and objectively using region of interest (ROI) analysis. Forty-six (61%) of 75 horses examined using MRI had lesions of the DDFT considered to be a major contributor to lameness. Thirty-two horses (43%) had primary DDFT injuries and 14 (19%) a combination of DDF tendonitis and navicular bone pathology. Lesions involved the insertional region of the tendon alone (n = 3), were proximal to the navicular bone (n = 23) or were at a combination of sites (n = 20). Lesion types included core lesions, focal and diffuse dorsal border lesions, sagittal plane splits, insertional injuries and lesions combined with other soft tissue injuries. Many horses had a combination of lesion types. Lameness was abolished by palmar digital analgesia in only 11 of 46 horses (24%). Twenty-one of 31 horses (68%) in Group I showed > 50% improvement in lameness after intra-articular analgesia of the DIP joint, whereas 11 of 12 horses (92%) in Group II had a positive response. Twelve of 18 horses (67%) in Group I had a positive response to analgesia of the navicular bursa. Nineteen horses had lesions of the DDFT extending proximal to the proximal interphalangeal joint seen using MRI, but these were identified ultrasonographically in only 2 horses. Scintigraphic abnormalities suggestive of DDFT injury were seen in 16 of 41 horses (41%), 8 in pool phase images and 8 in bone phase images. DDFT injuries are an important cause of lameness associated with pain arising from the digit in horses without detectable radiographic abnormalities. Lameness is not reliably improved by palmar digital analgesia, but may be improved by intra-articular analgesia of the DIP joint in at least 68% of horses. Ultrasonography is not sensitive in detecting lesions of the DDFT in the distal pastern region, but a combination of pool and bone phase scintigraphic images of the digit is helpful in some horses. Further follow-up information is required to determine the prognosis for horses with lesions of the DDFT in the digit and to establish whether this is related to lesion severity and/or location.

Optical testing by using the chromatic split of non-classical localization planes

When a spatially incoherent, periodic, quasi-monochromatic source illuminates a two-beam amplitude division interferometer verifying the equivalent sine condition, successive non-classical localization planes appear. If the radiation is polychromatic, then each plane splits and the plane corresponding to a given wavelength can be viewed distinctly by interposing an adequate filter. Thus, by interchanging filters and with no other change in the configuration, a non-classical localization plane is shifted. In the present paper this shift is employed to examine various transversal planes of a thick transparent specimen with a few phase disturbances distributed in its volume. Results obtained with a Wollaston prism are shown.

Branes, orientifolds and chiral gauge theories

We discuss some aspects of the physics of branes in the presence of orientifolds and the corresponding world-volume gauge dynamics. We show that at strong coupling orientifolds sometimes turn into bound states of orientifolds and branes, and give a world-sheet argument for the flip of the sign of an orientifold plane split into two disconnected parts by an NS5-brane. We also describe the moduli space of vacua of N = 2 supersymmetric gauge theories with symplectic and orthogonal gauge groups, and analyze a set of four-dimensional N = 1 supersymmetric gauge theories with chiral matter content using branes.

Application of the X-ray synergy method to analysis of room temperature compression of beryllium crystals

A recently-developed method (synergy method) was applied to zone-refined beryllium crystals compressed at room temperature. The synergy method, combining X-ray diffraction line profile analysis, X-ray topography and metallography, is capable of analyzing lattice defects in small volume elements of the crystal (10-μ diam cross-section by 5 mm in this case). Crystals oriented for basal slip, prism slip, andc-axis compression were examined. The existence of a columnar growth substructure was shown, which determined the response of the crystal to subsequent deformation. Inhomogeneous lattice rotation and basal plane bending induced by the interaction of basal slip dislocations with the columnar subgrain boundaries appeared to be a precursor of bend plane splitting. Crystals oriented for prism slip exhibited extensive twinning and those forc-axis compression gave rise to extensive basal slip. The predominance of basal slip in beryllium during room temperature deformation was found to be consistent with unique, anisotropic bonding characteristics.