The Regulations governing Materials Recovery Facilities (MRFs) in England require that they report on the quality of both the incoming mixed wastes and the single-stream recyclate products, with the ...results being made available on a public register. In this investigation, tests were conducted on a number of mixed wastes from different suppliers being processed at a qualifying MRF to evaluate how effective the Regulations (or MRF Code of Practice (MRF CoP)) were in generating useful, meaningful information. The empirical evidence obtained showed that MRF CoP in its current form has a number of serious flaws which detract from the validity and value of the reported operational data. The statutory definition of ‘material particles’ in the mixed wastes given in the MRF CoP means that compliance with the MRF CoP is impracticable, and in order to overcome this it will be necessary to re-word the definition of ‘material particles’. Empirical evidence also invalidated the explicit assumption made in the MRF CoP that the composition of the material particles is identical to that of the bulk materials, and consequently the basis for the mandatory apportioning of the weight of the material particles has no logical foundation and apportioning leads to distortion in the reported data. Changes will be required to the present statutory requirements for reporting operational results if the recorded information is to have meaning and relevance for stakeholders in the system.
The operation of qualifying materials recovery facilities (MRFs) in England is governed by the MRF code of practice (MRF CoP), which mandates certain sampling and testing practices for the mixed ...wastes being processed by the MRF. The results of this testing are required to be reported to the system regulator and are then made publicly available in a register. The MRF CoP is critically examined and certain aspects of the testing methodology are shown to be invalid, resulting in inaccurate information being included in the register. The current investigation looks at the extent of these inaccuracies and shows how they have very real financial implications for commercial operators of MRFs, especially where ‘shared basket’ contracts have been entered into, typically with local authorities.
Future space-based geodesy missions such as the Mass Change Mission and the Next Generation Gravity Mission are expected to rely on laser ranging as their primary instrument. Short-term laser ...frequency stability has previously been achieved on the GRACE Follow On mission by stabilizing the lasers to an optical cavity. The development of a technique to provide long-term laser frequency stability is expected to be required. We have previously demonstrated a technique to track long-term frequency changes by using measurements of the optical cavity’s free spectral range. In this paper, we calibrate this technique to absolute frequency by using an atomic reference. We have also validated an approach for on-ground calibration to allow the absolute frequency to be determined whilst in orbit.
We report on the first demonstration of time-delay interferometry (TDI) for LISA, the Laser Interferometer Space Antenna. TDI was implemented in a laboratory experiment designed to mimic the noise ...couplings that will occur in LISA. TDI suppressed laser frequency noise by approximately 10(9) and clock phase noise by 6×10(4), recovering the intrinsic displacement noise floor of our laboratory test bed. This removal of laser frequency noise and clock phase noise in postprocessing marks the first experimental validation of the LISA measurement scheme.
Satellite geodesy uses the measurement of the motion of one or more satellites to infer precise information about the Earth's gravitational field. In this work, we consider the achievable precision ...limits on such measurements by examining approximate models for the three main noise sources in the measurement process of the current Gravitational Recovery and Climate Experiment (GRACE) Follow-On mission: laser phase noise, accelerometer noise and quantum noise. We show that, through time-delay interferometry, it is possible to remove the laser phase noise from the measurement, allowing for almost three orders of magnitude improvement in the signal-to-noise ratio. Several differential mass satellite formations are presented which can further enhance the signal-to-noise ratio through the removal of accelerometer noise. Finally, techniques from quantum optics have been studied, and found to have great promise for reducing quantum noise in other alternative mission configurations. We model the spectral noise performance using an intuitive 1D model and verify that our proposals have the potential to greatly enhance the performance of near-future satellite geodesy missions.
Interferometric gravitational wave detectors are expected to be limited by shot noise at some frequencies. We experimentally demonstrate that a power recycled Michelson with squeezed light injected ...into the dark port can overcome this limit. An improvement in the signal-to-noise ratio of 2.3 dB is measured and locked stably for long periods of time. The configuration, control, and signal readout of our experiment are compatible with current gravitational wave detector designs. We consider the application of our system to long baseline interferometer designs such as LIGO.
Arm locking is a technique for stabilizing the frequency of a laser in an interspacecraft interferometer by using the spacecraft separation as the frequency reference. A candidate technique for ...future space-based gravitational wave detectors such as the Laser Interferometer Space Antenna, arm locking has been extensive studied in this context through analytic models, time-domain simulations, and hardware-in-the-loop laboratory demonstrations. In this paper we show the laser ranging interferometer instrument flying aboard the upcoming Gravity Recovery and Climate Experiment follow-on (GRACE-FO) mission provides an appropriate platform for an on-orbit demonstration of the arm-locking technique. We describe an arm-locking controller design for the GRACE-FO system and a series of time-domain simulations that demonstrate its feasibility. We conclude that it is possible to achieve laser frequency noise suppression of roughly 2 orders of magnitude around a Fourier frequency of 1 Hz with conservative margins on the system's stability. We further demonstrate that "pulling" of the master laser frequency due to fluctuating Doppler shifts and lock acquisition transients is less than 100 MHz over several GRACE-FO orbits. These findings motivate further study of the implementation of such a demonstration.
Arm-locking is a technique for stabilizing the frequency of a laser in an inter-spacecraft interferometer by using the spacecraft separation as the frequency reference. A candidate technique for ...future space-based gravitational wave detectors such as the Laser Interferometer Space Antenna (LISA), arm-locking has been extensive studied in this context through analytic models, time-domain simulations, and hardware-in-the-loop laboratory demonstrations. In this paper we show the Laser Ranging Instrument flying aboard the upcoming Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission provides an appropriate platform for an on-orbit demonstration of the arm-locking technique. We describe an arm-locking controller design for the GRACE-FO system and a series of time-domain simulations that demonstrate its feasibility. We conclude that it is possible to achieve laser frequency noise suppression of roughly two orders of magnitude around a Fourier frequency of 1Hz with conservative margins on the system's stability. We further demonstrate that 'pulling' of the master laser frequency due to fluctuating Doppler shifts and lock acquisition transients is less than 100MHz over several GRACE-FO orbits. These findings motivate further study of the implementation of such a demonstration.Arm-locking is a technique for stabilizing the frequency of a laser in an inter-spacecraft interferometer by using the spacecraft separation as the frequency reference. A candidate technique for future space-based gravitational wave detectors such as the Laser Interferometer Space Antenna (LISA), arm-locking has been extensive studied in this context through analytic models, time-domain simulations, and hardware-in-the-loop laboratory demonstrations. In this paper we show the Laser Ranging Instrument flying aboard the upcoming Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission provides an appropriate platform for an on-orbit demonstration of the arm-locking technique. We describe an arm-locking controller design for the GRACE-FO system and a series of time-domain simulations that demonstrate its feasibility. We conclude that it is possible to achieve laser frequency noise suppression of roughly two orders of magnitude around a Fourier frequency of 1Hz with conservative margins on the system's stability. We further demonstrate that 'pulling' of the master laser frequency due to fluctuating Doppler shifts and lock acquisition transients is less than 100MHz over several GRACE-FO orbits. These findings motivate further study of the implementation of such a demonstration.
PDF
