CHARACTERIZATION OF ϕ\phi-SYMMETRIC LORENTZIAN PARA-KENMOTSU MANIFOLDS

The purpose of the present paper is to explore the characteristics of the Lorentzian $\phi$-symmetric para-Kenmotsu manifold as an Einstein manifold. In this paper, we also study the parallel 2-form on the LP-Kenmotsu manifold (LP-Kenmotsu manifold is used in lieu of Lorentzian para-Kenmotsu manifold throughout the present research article). We explain that the conformally flat LP-Kenmotsu manifold is locally $\phi$-symmetric iff, it has constant scalar curvature

MEMS Gravity Sensors for Imaging Density Anomalies

Gravimeters measure small changes in the local gravitational acceleration. They are applied for environmental monitoring, oil and gas prospecting and defence and security. Gravimeters used in these applications have a remarkable sensitivity but at a cost of being bulky and very expensive. Recently, a micro-electrical mechanical system (MEMS) gravimeter has been developed, which was cheap, had a comparable sensitivity to commercial gravimeters and maintained its stability over long timescales (10−6 Hz). In this paper we discuss to replace the current shadow sensor readout with an on-chip interferometer. This new readout has a higher sensitivity so that the device can be more robust and reduces the system size. The design of this readout is discussed and the first experimental results are presented. The new readout improves the imaging capabilities of density anomalies of the device

Investigating biomechanical noise in neuroblastoma cells using the quartz crystal microbalance.

Quantifying cellular behaviour by motility and morphology changes is increasingly important in formulating an understanding of fundamental physiological phenomena and cellular mechanisms of disease. However, cells are complex biological units, which often respond to external environmental factors by manifesting subtle responses that may be difficult to interpret using conventional biophysical measurements. This paper describes the adaptation of the quartz crystal microbalance (QCM) to monitor neuroblastoma cells undergoing environmental stress wherein the frequency stability of the device can be correlated to changes in cellular state. By employing time domain analysis of the resulting frequency fluctuations, it is possible to study the variations in cellular motility and distinguish between different cell states induced by applied external heat stress. The changes in the frequency fluctuation data are correlated to phenotypical physical response recorded using optical microscopy under identical conditions of environmental stress. This technique, by probing the associated biomechanical noise, paves the way for its use in monitoring cell activity, and intrinsic motility and morphology changes, as well as the modulation resulting from the action of drugs, toxins and environmental stress.This is the author accepted manuscript. The final version is available from Royal Society Publishing via http://dx.doi.org/10.1098/rsif.2014.138

Normalising Flows for Bayesian Gravity Inversion

Gravity inversion is a commonly applied data analysis technique in the field of geophysics. While machine learning methods have previously been explored for the problem of gravity inversion, these are deterministic approaches returning a single solution deemed most appropriate by the algorithm. The method presented here takes a different approach, where gravity inversion is reformulated as a Bayesian parameter inference problem. Samples from the posterior probability distribution of source model parameters are obtained via the implementation of a generative neural network architecture known as Normalising Flows. Due to its probabilistic nature, this framework provides the user with a range of source parameters and uncertainties instead of a single solution, and is inherently robust against instrumental noise. The performance of the Normalising Flow is compared to that of an established Bayesian method called Nested Sampling. It is shown that the new method returns results with comparable accuracy 200 times faster than standard sampling methods, which makes Normalising Flows a suitable method for real-time inversion in the field. When applied to data sets with high dimensionality, standard sampling methods can become impractical due to long computation times. It is shown that inversion using Normalising Flows remains tractable even at 512 dimensions and once the network is trained, the results can be obtained in $O(10)$ seconds.Comment: 14 pages, 6 figures, submitted for publication in Computers & Geosciences Journa

''Performance Analysis Under Double Sided Clipping and Real Time Implementation of DCO-GFDM in VLC Systems

In the context of visible light communications (VLC), DC biased optical generalized frequency division multiplexing (DCO-GFDM) is a recently emerged waveform relying on block based transmission and employs pulse shaping using a circularly rotating prototype filter. In this work, we analyze the bit error rate (BER) performance of DCO-GFDM under double sided clipping induced by front end light emitting diode (LED) transmitters. The effect of clipping on BER performance is studied under different biasing conditions for different prototype filters. Additionally, we experimentally verify the real time performance of DCO-GFDM using different pulses. Simulations are performed in MATLAB software and experiments are conducted in a Lab-view environment using hardware. Two independent universal software radio peripherals (USRP)s are utilized as transmitter and receiver boards. It is observed that the simulation results match well with the corresponding theoretical results. Meanwhile, the experimentally achieved results for error vector magnitude (EVM), the received constellations, and the received spectrum along with BER in different cases are presented for the validation of DCO-GFDM waveform and are compared with DCO orthogonal frequency division multiplexing (DCO-OFDM). © 1983-2012 IEEE

Optical Readout Design for a MEMS Semi-Absolute Pendulum Gravimeter

Gravimetry has many useful applications from volcanology to oil exploration; being a method able to infer density variations beneath the ground. Therefore, it can be used to provide insight into subsurface processes such as those related to the hydrothermal and magmatic systems of volcanoes. Existing gravimeters are costly and heavy, but this is changing with the utilisation of a technology most notably used in mobile phone accelerometers: MEMS –(Microelectromechanical-systems). Glasgow University has already developed a relative MEMS gravimeter and is currently collaborating with multiple European institutions to make a gravity sensor network around Mt Etna - NEWTON-g. A second generation of the MEMS sensor is now being designed and fabricated in the form of a semi-absolute pendulum gravimeter. Gravity data for geodetic and geophysical use were provided by pendulum measurements from the 18th to the 20th century. However, scientists and engineers reached the limit of fabrication tolerances and readout accuracy approximately 100 years ago. With nanofabrication and modern electronics techniques, it is now possible to create a competitive pendulum gravimeter again. The pendulum method is used to determine gravity values from the oscillation period of a pendulum with known length. The current design couples two pendulums together. Here, an optical shadow-sensor pendulum readout technique is presented. This employs an LED and split photodiode set-up. This optical readout can provide measurements to sub-nanometre precision, which could enable gravitational sensitivities for useful geophysical surveying. If semi-absolute values of gravity can be measured, then instrumental drift concerns are reduced. Additionally, the need for calibration against commercial absolute gravimeters may not be necessary. This promotes improved accessibility of gravity measurements at an affordable cost

Design and Testing of a MEMS Semi-Absolute Pendulum Gravimeter

Gravimetry has many useful applications from volcanology to oil exploration; being a method able to infer density variations beneath the ground. Therefore, it can be used to provide insight into subsurface processes such as those related to the hydrothermal and magmatic systems of volcanoes. Existing gravimeters are costly and heavy, but this is changing with the utilisation of a technology most notably used in mobile phone accelerometers: MEMS – (Microelectromechanical-systems). A team at the University of Glasgow has already developed a MEMS relative gravimeter and is currently collaborating with multiple European institutions to make a gravity sensor network around Mt Etna - NEWTON-g. A second generation of the MEMS sensor is now being designed and fabricated in the form of a semi-absolute pendulum gravimeter. Gravity data for geodetic and geophysical use were provided by pendulum measurements from the 18th to the 20th century. However, scientists and engineers reached the limit of fabrication tolerances and readout accuracy approximately 100 years ago. With nanofabrication and modern electronics techniques, it is now possible to create a competitive pendulum gravimeter again. In this presentation the design and fabrication techniques of a new MEMS pendulum gravimeter will be outlined. The design comprises two pendula, which oscillate in anti-phase to reduce the influence of seismic noise. Nanofabrication methods have been used to create both flexure and knife-edge pivot points. An optical shadow-sensor has been developed to monitor the position of the pendula. This optical readout can provide measurements to sub-nanometre precision. Data collected from laboratory testing will be presented, demonstrating the progression being made towards a prototype field device. This data will include measurements of the influence of tilt-sensitivity and the seismic and shadow sensor noise floors. Altitude tests of the free-air effect will be presented to demonstrate the current sensitivity of the device. If semi-absolute values of gravity can be measured, then instrumental drift concerns are reduced. Additionally, the need for calibration against commercial absolute gravimeters may not be necessary. This promotes improved accessibility of gravity measurements at an affordable cost

pengaruh serbuk gergaji kayu jati terhadap kekuatan mekanis komposit partikel

Limbah serbuk gergaji hasil proses penggergajian kayu log maupun papan, sangatlah melimpah dan belum termanfaatkan secara maksimal, penelitian ini bertujuan untuk mengetahui pengaruh perbandingan fraksi volume serbuk gergaji kayu jati terhadap kekuatan mekanis komposit partikel. Resin yang digunakan dalam penelitian ini adalah Poliester tak jenuh BQTN 157 dan serbuk gergaji yang digunakan adalah limbah penggergajian kayu jati, perbandingan fraksi volume yang digunakan adalah 90%:10%, 80%:20%, 70%:30%, 60%:40%, ukuran serbuk gergaji kayu jati adalah ± 0,84mm – 1mm. Proses pengeringan serbuk gergaji dengan suhu 90 ºC selama 1 jam. Campuran resin katalis dan serbuk gergaji kayu jati sesuai dengan perhitungan fraksi volume yang telah ditentukan. Proses pencetakan menggunakan metode hand lay-up dan diberikan tekanan sebesar 1 MPa lama waktu penekanan 15 menit, proses pengeringan komposit selama 24 jam, komposit dilakukan proses post curring dengan suhu 62ºC waktu penahanan 4 jam. Dimensi spesimen uji tarik mengikuti standar ASTM D 638 dan spesimen uji bending mengikuti standar ASTM D 790. Hasil penelitian kekuatan tarik dan kekuatan bending tertinggi didapatkan pada perbandingan fraksi volume 90% : 10% yaitu 17,14 MPa dan 27,62 MPa, semakin bertambahnya serbuk kayu mengakibatkan kekuatan tarik dan bending menurun, untuk perbandingan fraksi volume 60% : 40 % masih masuk kedalam standar SNI 03-215-2006 dan SNI 03-2015-1996 untuk pengujian bending dan pengujian tarik. Semakin bertambah serbuk gergaji mengakibatkan nilai densitas semakin menurun