TMD Technologies (United Kingdom)

The results of a marine trial for a cold atom system for inertial navigation (HARLEQUIN) is presented. The system is a deployable atom interferometer demonstrator for navigation using inertial measurements. The interferometer is a grating based, Mach-Zehnder interferometer using rubidium-87 to make measurements of acceleration in a single axis. The output of the quantum sensor is used to condition classical sensors, in a quantum-classical hybrid measurement scheme. The subsystems of HARLEQUIN have been tested aboard a marine platform operated by the UK General Lighthouse Authority, to determine its performance in marine environments and informing an upgrade path to a fully deployable quantum sensor. Presented are results from the trial and upgrade path towards a fully deployable quantum sensor.

This paper elaborates on the design aspects of the first prototype of a 26–40 GHz wideband helix traveling wave tube (TWT) being developed at CPI-TMD Technologies Limited. The TWT is designed to achieve an output power exceeding 100 watts throughout the specified frequency range. A preliminary design has been accomplished for both the radio frequency (RF) circuit, which encompasses the loaded helical slow wave structure, couplers and windows, as well as the beam optics, including components such as the electron gun, magnetics and collector. The complexities faced in developing such a high-frequency helix TWT are thoroughly examined, accompanied by a design that is deemed practical for manufacturing purposes. Furthermore, the development of the beam stick and the slow wave structure for the initial prototype TWT is in progress.

Flow boiling heat transfer enhancement using porous coatings in microchannels has been experimentally investigated with HFE-7200. Results of the coated microchannel heat sink were compared to baseline results in a plain, micro-milled copper microchannel heat sink at similar operating conditions, namely inlet pressure of 1 bar, mass flux of 200 – 400 kg/m2 s and inlet subcooling of 10 K at wall heat fluxes between 24.5 kW/m2 to 206.6 kW/m2. Flow visualisation results and SEM surface analysis are presented. The coated surface was densely populated with well-defined cavities between 0.6 µm to 3.3 µm wide. The plain channels had fewer cavities for a given area and these were larger, i.e. up to 6 µm. Bubble generation frequency in the coated channels is significantly higher than in the plain channels due to the presence of more favourable nucleation sites on the coated surface. Flow pattern development occurred similarly in both heat sinks, namely bubbly to slug, churn and annular flow with increasing heat flux, with earlier flow pattern transitions in the coated heat sink. Enhancement in microchannel flow boiling heat transfer was shown to be influenced by mass velocity and may reach up to 44% at low heat fluxes, where the nucleate boiling mechanism is dominant. It diminishes with increasing heat flux, corresponding to nucleate boiling suppression following flow regime transition. Pressure drop increase posed by the coated heat sink is relatively small in terms of overall system power consumption but appears to be influenced by mass flux, pressure oscillations as well as channel rewetting behaviour.

Compact vacuum systems are key enabling components for cold atom technologies, facilitating extremely accurate sensing applications. There has been important progress toward a truly portable compact vacuum system; however, size, weight, and power consumption can be prohibitively large, optical access may be limited, and active pumping is often required. Here, we present a centiliter-scale ceramic vacuum chamber with He-impermeable viewports and an integrated diffractive optic, enabling robust laser cooling with light from a single polarization-maintaining fiber. A cold atom demonstrator based on the vacuum cell delivers 107 laser-cooled 87Rb atoms per second, using minimal electrical power. With continuous Rb gas emission, active pumping yields a 10−7 mbar equilibrium pressure, and passive pumping stabilizes to 3×10−6 mbar with a 17 day time constant. A vacuum cell, with no Rb dispensing and only passive pumping, has currently kept a similar pressure for more than 500 days. The passive-pumping vacuum lifetime is several years, which is estimated from short-term He throughput with many foreseeable improvements. This technology enables wide-ranging mobilization of ultracold quantum metrology.

In this paper, practical implementation aspects of recently proposed ultra compact inline waveguide bandpass filters that utilise stopband performance of their pseudo-elliptic responses through positive sign bypass coupling are explored. Fundamental working principles are outlined from different perspectives and a number of X band filter samples are described in details, together with fabrication process using a pair of thin metal inserts positioned parallel along two different B-planes of a straight waveguide section. Developing from the core strengths of compactness, being 70% smaller than conventional B-plane filters, and ease of fabrication, discourse is continued by exposing the filters to different application challenges. It is demonstrated that the proposed structure is not only suitable for narrowband designs, giving a sample of a filter with 12% fractional bandwidth, still maintaining dimensions that allow fabrication with the same machining equipment. In addition, flexibility of producing the same filter response by modifying dimensions of different elements is shown. Sensitivity analysis is carried out and an approach to fine mechanical filter tuning is proposed. Furthermore, an example of higher degree filter of the fifth order is presented to illustrate the ability of the filter to meet demanding real-life specifications.

The aim of this prospective study was to test a mathematical method of measuring the malrotation of pediatric distal radius fractures (PDRFs) from direct radiographs. A total of 70 pediatric patients who presented at the Emergency Department with a distal radius fracture were evaluated. For 38 selected patients conservative treatment for PDRF was planned. Anteroposterior and lateral radiographs were taken of all of the patients for comparison before and after reduction. Radius bone diameters were measured in the coronal and sagittal planes on the healthy and fractured sides. Using the diameter values on the healthy side and the new diameter values on the fractured side in the rotation formula, the degree of malrotation between the fracture ends was calculated. The mean follow-up period was 13.5 months. Patients’ mean age was 10.00 ± 3.19 years (range, 4–12 years). The rotation degree in the sagittal plane significantly differed between the proximal (26.52°±2.84°) and distal fracture ends (20.96°±2.73°) (P = 0.001). The rotation degree in the coronal plane significantly differed between the proximal (26.70°±2.38°) and distal fracture ends (20.26°±2.86°) (P = 0.001). The net rotation deformity of the fracture line was determined to be 5.55°± 3.54° on lateral radiographs and 5.44°± 3.35° on anteroposterior radiographs, no significant difference was observed between measurements (P >0.05). The malrotation deformity in PDRF occurs with greater rotation in the proximal fragment than in the distal fragment. The net rotation deformity created between the fracture ends can be calculated on direct radiographs.Level of Evidence: Diagnostic, Level II

There are some recommendation sites for many popular amusement parks. It is difficult for visitors to find the best way of moving about with enjoyment, excitement and relaxation. Our research is to model to find an optimal routing of amusement parks with fast pass constraint.

This study attempted to identify baseline predictors of positive outcome of arthrocenteses plus hyaluronic acid injections in degenerative temporomandibular joint disease (TMJ DJD). Ninety (n=90) consecutive patients with Research Diagnostic Criteria for Temporomandibular Disorders TMJ osteoarthritis (RDC/TMD 1.0 Axis I Group IIIb) underwent a cycle of five arthrocenteses with injections of 1mL hyaluronic acid and were followed up for 3months. Eight potential predictors of positive treatment outcome (sex, age, pain duration, baseline pain at chewing, presence of uni- or bilateral arthritis, presence of other concurrent RDC/TMD diagnoses, type of intervention and tolerability of treatment) were included in a logistic regression model to identify baseline predictors of treatment effectiveness. At follow-up, 85·6% of patients improved with respect to baseline VAS values, and 64·4% had a 50% or more decrease (positive outcomes). Correlation with positive outcomes existed only for unilateral osteoarthritis, and the logistic regression identified the side of arthritis (unilateral/bilateral) as the only predictor of positive treatment outcome (P=0·032). The achievement of any treatment improvement was predicted by high baseline pain levels (P=0·016). The regression models explained only 7·7-15% of the variance in the outcome variable. The attempts to find predictors of positive treatment outcome with HA injections for TMJ degenerative joint disease have been successful only in part. The search for other outcome predictors is likely to benefit from the assessment of psychosocial features associated with TMJ disorders.

The paper describes the use of numerical methods to precisely predict the characteristics of ring-Loop & ring-Bar slow wave structures and provides examples of the close agreement obtainable between predicted and actual measured performance of TWTs. The microwave properties of the structures have been modelled using a commercially available 3D, high frequency electromagnetic, software package, founded on use of the finite element method.