Oxidation-reduction potential (ORP) sensors would constitute a robust surveillance and control solution for aeration external carbon dosing in wastewater biological treatment processes if clear correlation exists between the ORP values process variables (e.g., dissolved oxygen (DO), nitrate, chemical demand (COD). In this study, other water quality were analyzed, principal component analysis (PCA) of variance used to study relationships main reactive substances under anoxic conditions....

Multipass cell (MPC), with a long effective optical path length (OPL), is an method to improve measurement sensitivity in laser absorption spectroscopy for trace gas sensing. We present space equation (SE) design MPC, which can solve inaccuracy caused by using paraxial-matrix (PM) method. The location and dimension of light spot pattern be calculated accurately intuitively through SE Meanwhile, actual OPL calculated, reduce the interference effect, direction each ray obtained accurately,...

Natural gas hydrates, as a clean and green energy source, are widely distributed in extreme environments near the seabed. They release relatively low concentrations of carbon dioxide dissolved water. Therefore, precise detection changes concentration water is an effective means to accurately characterize distribution natural hydrates. Compared direct absorption spectroscopy near-infrared systems, tunable diode laser spectroscopy-wavelength modulation (TDLAS-WMS) system, which operates...

Inspired by the basic theory of Fruit Fly Optimization Algorithm, in this paper, cat mapping was added to original algorithm, and individual distribution evolution mechanism fruit fly population were improved order increase search speed accuracy. The flowchart algorithm drawn show its procedure. Using classical test functions, simulation optimization results that has faster more reliable ability. then combined with sparse decomposition used processing fouling detection ultrasonic signals...

Residence times difference (RTD) fluxgate magnetometers measure the magnetic field using time between positive and negative pulses of induced voltage signal in domain. Sensitivity is one most important parameters to evaluate performance magnetometers. According our best knowledge existing literature, for RTD sensors, there are no available models that can clearly set up relationships physical an sensor sensitivity. Moreover, relationship sensitivity excitation conditions very complicate,...

In geochemical applications, carbon dioxide isotope abundance should be accurately measured. However, many challenges must overcome in field such as the interference from harsh environment or influence of various underground overflow gases. this study, a CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> sensing system using subspace identification Hammerstein model (SIHM) was investigated to achieve better accuracy than current method...

Carbon monoxide (CO), as a dangerous emission gas, is easy to accumulate in the complex underground environment and poses serious threat safety of miners. In this paper, sensor using quantum cascade laser with an excitation wavelength 4.65 μm light source, compact multiple reflection cell path length 12 m introduced detect trace CO gas. The adopts long optical differential absorption spectroscopy technique (LOP-DAST) obtains minimum detection limit (MDL) 108 ppbv by comparing residual...

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In order to ensure the personal safety and production of petrochemical enterprises, it is necessary detect methane combustible gas in production, storage transportation facilities give timely alarm. Based on TDLAS telemetry technology, this paper studies driving circuit DFB laser with as detection target. The external digital analog converter controlled by FPGA generate corresponding sawtooth scan signal sine wave modulation signal. Among them, frequency 1 kHz-100 kHz, amplitude 0-5V,...

In heat exchange fouling ultrasonic testing, the time-domain signal waveform often contains high aliasing due to small thickness or order echo interference, and so forth. This paper studies method of acquiring time flight from testing with presents that combined Wiener deconvolution cumulative spectrum estimation. For reference distortion problem, which may exist in real application, an iterative correction process is introduced form Incremental algorithm. Simulation experimental results...

Accurate measurement of carbon isotope abundance is extremely important for geochemical applications. In the seismic zone, error caused by variable gas temperature must be compensated. this study, a <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> CO <sub xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> sensor using gradient field compensation (TGFC) method investigated to improve accuracy measurement. The theoretical model combined...

A seismic activity monitoring instrument is required in gas geochemical exploration (GGE) to measure methane (CH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> ) and carbon dioxide (CO xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> near the geological fault zone. prototype of CH CO sensing system based on wavelength modulation spectroscopy, which can achieve a high-accuracy, wide-range, <italic...

High-accuracy multi-component gas sensing systems are required to monitor the geochemical in atmosphere for early warning of earthquakes. On basis an achromatic model, structure is developed using ridged-shaped windows eliminate optical system dispersion. A passive locking designed based on a multi-layer rotationally symmetrical model lock cavity state. multipass absorption cell (PLAMAC) and structures improve transmission performance environment adaptability. temperature control subsystem...