Output spectrum computation for a square-law diode detector

The effect of source resistance on the output spectrum of a square-law diode detector is discussed. An analytical expression is presented for the incremental current-voltage characteristic of the detector, including the effect of the source resistance. Using this expression, analytical expressions are obtained for the output spectrum of the detector in terms of Bessel functions. Under the small-signal conditions usually prevailing, the spectrum computation requires only simple hand calculations. Using the expressions, a better insight into the effect of the source resistance on the output spectrum of the diode detector can be obtained     

Compact and high-precision range finder with wide dynamic range andits application

Described is a new range finder using a self-mixing laser diode (SM-LD). The range finder has a high accuracy of ±0.15% and a wide dynamic range of 0.2-1 m using only one sensor head. Compared to ultrasonic range finders, the light beam of this laser range finder can be focused and scanned. The feasibility study shows a possible application of the range finder to a visual sensor of a robot. The proposed range finder has been successfully applied as an infrared (IR) active type range finder of a single-lens reflex camera     

High dynamic range bio-molecular ion microscopy with the Timepix detector

Highly parallel, active pixel detectors enable novel detection capabilities for large biomolecules in time-of-flight (TOF) based mass spectrometry imaging (MSI). In this work, a 512 × 512 pixel, bare Timepix assembly combined with chevron microchannel plates (MCP) captures time-resolved images of several m/z species in a single measurement. Mass-resolved ion images from Timepix measurements of peptide and protein standards demonstrate the capability to return both mass-spectral and localization information of biologically relevant analytes from matrix-assisted laser desorption ionization (MALDI) on a commercial ion microscope. The use of a MCP-Timepix assembly delivers an increased dynamic range of several orders of magnitude. The Timepix returns defined mass spectra already at subsaturation MCP gains, which prolongs the MCP lifetime and allows the gain to be optimized for image quality. The Timepix peak resolution is only limited by the resolution of the in-pixel measurement clock. Oligomers of the protein ubiquitin were measured up to 78 kDa.     

Frequency-selective Josephson detector: Power dynamic range at subterahertz frequencies

The power dynamic range of an YBa₂Cu₃O_7−x frequency-selective Josephson detector for the Hilbert-transform spectroscopy was experimentally studied in the subterahertz frequency range. At a temperature of 80 K, the dynamic range of 2×10⁵ was achieved at a noise equivalent power of 8×10⁻¹⁵ W/Hz^1/2.     

Simultaneous high gain and wide dynamic range in a model of bacterial chemotaxis

Mathematical modelling and sensitivity analysis of the signal transduction pathway underlying chemotaxis in Escherichia coli suggests a mechanism for high sensitivity over a dynamic range of five orders of magnitude. The analysis reveals that the enhancement in sensing ability occurs in the signal receiving module that is comprised of ligand binding, change of occupancy and change of receptor activities. The clustering of receptors contributes to the signal capability by exploiting interactions between receptors for the activity change. The role of the autophosphorylation of the histidine kinase CheA and the phosphotransfer to the response regulator protein CheY is to relay the signal to the cell's motor apparatus at little expense to the sensitivity at low stimuli. The results also provide insight on the values of kinetic parameters that maximise the efficiency of the signalling pathway.     

Automatic complex for determining static and dynamic characteristics of pressure transducers over a wide temperature range

The possibility of using the electrohydraulic effect for dynamic calibration of pressure transducers over a wide range of temperatures, including cryogenic, is examined along with a series of related questions pertaining to theory, instrumentation, and software.Translated from Izmeritel'naya Tekhnika, No. 6, pp. 40–43, June, 1993.     

Count rate and dynamic range of an X-ray imaging system with MCP detector

X-ray imaging system with edge-on MCP detector has recently been evaluated for potential application in medical imaging. Although this system has been able to provide good quality images, its clinical implementation is limited by its low count rate. The system count rate was limited by a delay line position encoding electronics, which processes the events serially. The count rate of the MCP was also limited because of high gain required for delay line electronics. In this work, the count rate and dynamic range of the system was evaluated. The count rate limitation due to readout electronics and MCP was measured separately. Pulse counting and charge integrating modes of the MCP detector was used. Photon beams for these measurements were generated using an X-ray tube at 50 and 90 kVp peak potentials with 41 and 75 keV average photon energies, respectively. The electronics dead time was measured to be 20% at 200 kHz total system count rate. In addition, 15–30% of the photon signals were not detected by delay line electronics due to exponential pulse height distribution of the MCP signals. The exponential pulse height distribution of the MCP was due to the edge on illumination mode of the MCP and the high energy X-ray photon beam. Image artifacts due to dead time and signal loss were evaluated. Multichannel ASIC readout electronics was considered as a potential solution to the count rate and dynamic range problem. It was shown that the edge-on MCP detector can operate in pulse counting mode at low gains of 10⁴–10⁵ e/photon required for ASIC electronics. It was also shown that at this low gain, the MCP count rate can be increased up to 1.33×10⁶ count/s/pixel, for 100 μm detector pixels, which is appropriate for clinical X-ray imaging.     

Curved focal plane detector array for wide field cameras

Miniaturization is the main goal for system design in future cameras. This paper offers a novel method to scale down the optical system and to improve the image quality. As with the human retina, the detector array is spherically bent to fit the curved image surface; so the field curvature aberration is directly suppressed, leading to a better resolution and a simplified optical design. By thinning the substrate, the device is monolithically curved without modifying the fabrication process of the active pixels. Optical characterizations have been performed on planar and curved focal plane based cameras to illustrate the optical advantages of detector array curvature.     

A fast job scheduling system for a wide range of bioinformatic applications

Bioinformatic tools are often used by researchers through interactive Web interfaces, resulting in a strong demand for computational resources. The tools are of different kind and range from simple, quick tasks, to complex analyses requiring minutes to hours of processing time and often longer than that. Batteries of computational nodes, such as those found in parallel clusters, provide a platform of choice for this application, especially when a relatively large number of concurrent requests is expected. Here, we describe a scheduling architecture operating at the application level, able to distribute jobs over a large number of hierarchically organized nodes. While not contrasting and peacefully living together with low-level scheduling software, the system takes advantage of tools, such as SQL servers, commonly used in Web applications, to produce low latency and performance which compares well and often surpasses that of more traditional, dedicated schedulers. The system provides the basic functionality necessary to node selection, task execution and service management and monitoring, and may combine loosely linked computational resources, such as those located in geographically distinct sites.     

A general equation for the dynamic viscosity of a binary mixture of organic liquids over a wide range in state parameters

Experimental data have been used in a general equation for the dynamic viscosity of a binary system as a function of temperature, pressure, and concentration.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 51, No. 5, pp. 737–741, November, 1986.     

Efficiency calibration of a HPGe detector in the [46.54–2000] keV energy range for the measurement of environmental samples

Here we describe a general method of calibrating the efficiency of a Ge γ-ray spectrometer. The method, which is based on the work of Quintana and Fernández (Appl. Radiat. Isot. 47 (1996) 911), can now be applied to many different experimental set-ups including both liquid and solid environmental samples. The method requires two different types of experimental inputs. Firstly, it requires measurements with radioactive sources emitting cascades of γ rays covering the energy range of interest. Secondly, it requires measurements with sources emitting isolated γ rays in order to provide coincidence-summing corrections. On this basis, we establish a general function to describe the energy dependence of the efficiency for the particular geometry and source matrix. The method has been applied to 11 different experimental arrangements to provide efficiency calibrations over the range 46.54–2000 keV with associated uncertainties ranging from 0.1% to 1.8%. This allows high precision measurements with environmental samples, which often have very low activities.     

Estimation of dynamic fatigue strengths in brittle materials under a wide range of stress rates

This paper aims to statistically estimate the dynamic fatigue strength in brittle materials under a wide range of stress rates. First, two probabilistic models were derived on the basis of the slow crack growth (SCG) concept in conjunction with two-parameter Weibull distribution. The first model, Model I, is a conventional probabilistic delayed-fracture model based on a concept wherein the length of the critical crack growth due to SCG is enough larger than the initial crack length. For the second model, Model II, a new probabilistic model is derived on the basis of a concept wherein the critical cracks have widely ranging lengths. Next, a four-point bending test using a wide range of stress rates was performed for soda glass and alumina ceramics. We constructed fracture probability–strength–time diagrams (F–S–T diagrams) with the experimental results of both materials using both models. The F–S–T diagrams described using Model II were in good agreement with plots of the fracture strength and the fracture time of both materials more so than Model I.     

A phenazine anode for high-performance aqueous rechargeable batteries in a wide temperature range

Aqueous rechargeable batteries are a possible strategy for large-scale energy storage systems. However, limited choices of anode materials restrict their further application. Here we report phenazine (PNZ) as stable anode materials in different alkali-ion (Li⁺, Na⁺, K⁺) electrolyte. A novel full cell is assembled by phenazine anode, Na_0.44MnO₂ cathode and 10 M NaOH electrolyte to further explore the electrochemical performance of phenazine anode. This battery is able to achieve high capacity (176.7 mAh·g^?1 at 4 C (1.2·Ag^?1)), ultralong cycling life (capacity retention of 80% after 13,000 cycles at 4 C), and excellent rate capacity (92 mAh·g^?1 at 100 C (30 A·g^?1)). The reaction mechanism of PNZ during charge—discharge process is demonstrated by in situ Raman spectroscopy, in situ Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations. Furthermore, the system is able to successfully operate at wide temperature range from ?20 to 70 °C and achieves remarkable electrochemical performance.