Host Selection of Spring Tiphia (Tiphia vernalis) and Summer Tiphia (Tiphia popilliavora), Natural Enemies of Japanese and Oriental Beetles

Japanese beetle, Popillia japonica Newman, and oriental beetle, Anomala orientalis (Waterhouse) (Coleoptera: Scarabaeidae) are major turfgrass pests in United States. Tiphia vernalis Rohwer and Tiphia popilliavora Rohwer (Hymenoptera: Tiphiidae) were introduced as biocontrol agents against these beetles. To test the attractiveness of Tiphia wasps to herbivore induced plant volatiles, two choice bio assays were conducted. Results showed that both T. vernalis and T. popilliavora were strongly attracted to volatiles emitted by grub-infested tall fescue (Festuca arundinacea Schreb.) and Kentucky bluegrass (Poa pratensis L.) over healthy grasses. The elevated levels of terpenes emitted by grub-infested Kentucky bluegrass and tall fescue coincided with the attractiveness to the tiphiid wasps. Below-ground host location choice tests revealed that T. popilliavora wasps can successfully discriminate between the trails containing body odor or frass of P. japonica grubs and trails without cues. Host cue detection at varying soil depths experiment revealed that each species of Tiphia can discriminate between the Y-tube arms with and without cues when the cues of P. japonica were buried at a depth of 2 cm but not at a depth of 5 cm. Analysis of Tiphia parasitoids preovipositional behaviors and of their scarab host defensive responses experiment showed that female T. vernalis spent significantly longer time trying to sting A. orientalis grubs than P. japonica grubs in order to paralyze them. Third-instar grubs of A. orientalis spent significantly longer time on defensive behaviors when they were attacked by T. vernalis which likely cause wasps to spend longer time trying to sting A. orientalis grubs. We examined the influence of turfgrass species on development and survival of oriental beetle grubs and their parasitoid T. popilliavora wasps. Grub feeding on perennial ryegrass and endophyte-free tall fescue resulted in highest mean grub survival, weight gain, and number of third instars compared to Kentucky bluegrass. The survival of T. popilliavora larvae was significantly greater on A. orientalis grubs that had been exposed to roots of endophyte-free tall fescue and perennial ryegrass compared to that of Kentucky bluegrass

Method to visualise and measure individual modes in a few moded fibre

Coupling between the propagating modes and radiation modes of a FMF enables separation and measurement of the properties of the light in each mode independently. A method using prism coupling from a side-polished fibre is described to access and select individual modes

All fiber components for multimode SDM systems

Fiber based mode converters and mode splitters are important elements in the FMF mux./demux. Long Period Gratings (LPGs) have been investigated and results presented together with a potential technique for real time mode monitoring during manufacture

Complementary analysis of modal content and properties in a 19-cell hollow core photonic band gap fiber using Time-of-Flight and S2 techniques

We study the rich multimode content of an ultra-low loss hollow core photonic bandgap fiber using two complementary techniques which allow us to investigate both short and long propagation distances. Several distinct vector modes are clearly identified, with evidence of low intermodal coupling and distributed scattering

Numerical modelling of hydraulic fracturing in naturally fractured rock

This thesis presents a novel approach for hydro-geomechanical modelling of fractured rocks by linking a solid mechanics model with a multi-fluids and multi-phase fluid flow model using the immersed-body approach for coupling fluids and solids. The method uses conservative mesh-to-mesh projection to pass variables between an mesh adapting multi-phase fluid-flow solver and a deformation and fracturing solid geomechanics solver. The adaptive mesh refining and coarsening of the fluid model further permits the flow within and near to fractures (e.g. localised flow, leak off) to be represented using a locally refining mesh. The mass conservation between the coupled fluid and solid fields is ensured through a globally conservative Galerkin projection-based mesh interpolation. To simulate the nonlinear deformation of natural fractures in rock, the geomechanics model is integrated with a joint constitutive model that can capture the aperture variation of rough fractures under normal and/or shear loading. The solid mechanics is modelled using a Lagrangian specification in a Finite-Discrete Element Method (FEMDEM) framework called Solidity Project. Multi-phase (incompressible and compressible) fluid flow in porous media is considered through a Control-Volume Finite-Element Method (CV-FEM) based Darcy Flow solver and is called the Imperial College Finite-Element Reservoir Simulator (IC-FERST). The one-way (solid to fluid) coupled model is validated against analytical solutions for single-phase flow through a smooth/rough fracture and other reported numerical solutions for multi-phase flow through intersecting fractures. Examples of modelling single- and multi-phase flows through fracture networks under in-situ stresses are further presented, illustrating the important geomechanical effects on the hydrological behaviour of fractured porous media. The two-way coupled model for fluid-driven fracturing is validated using available laboratory hydraulic fracturing experiments in un-stressed and stressed regimes. The coupling framework is extended to three-dimensional, coupled modelling of flow modelling and fluid-driven fracturing through the creation of locally enriched shell-mesh elements at pre-existing and new fracture surfaces. The coupled framework can be extended to other perturbed states than fluid pressure driven fracturing, such as during underground excavation and dewatering. Application of the coupled framework to assess the stability of tunnel walls during tunnel excavation in saturated highly-fractured porous rock has been investigated in the context of deep-geological disposal of nuclear waste.Open Acces

A Fully Coupled Discrete-Continuous Numerical Approach for Hydrofracture Interaction and Flow Modelling

<p>In this work a coupled continuum and discontinuum based numerical approach is developed to study fracture initiation together with fracture propagation.</p

Fiber LPG mode converters and mode selection technique for multimode SDM

The use of multimode fibers in mode division multiplexed space-division multiplexing systems offers one solution to the capacity limitations of single-mode fiber transmission. Passive components to control the individual modes in few-mode fiber (FMF) are key elements to build more complex modules and components necessary for a high performance system. Fiber-based mode converters are important elements in the FMF mux/demux, and long-period gratings have been investigated to provide mode conversion in two- and four-mode fibers. A method to separate and monitor the modes in real time is described as the basis of a method to measure the individual modal performance of a component during fabrication

Modelling stress-dependent single and multi-phase flows in fractured porous media based on an immersed-body method with mesh adaptivity

This paper presents a novel approach for hydromechanical modelling of fractured rocks by linking a finite-discrete element solid model with a control volume-finite element fluid model based on an immersed-body approach. The adaptive meshing capability permits flow within/near fractures to be accurately captured by locally-refined mesh. The model is validated against analytical solutions for single-phase flow through a smooth/rough fracture and reported numerical solutions for multi-phase flow through intersecting fractures. Examples of modelling single- and multi-phase flows through fracture networks under in situ stresses are further presented, illustrating the important geomechanical effects on the hydrological behaviour of fractured porous media