Quantitative Analysis and Correction of Temperature Effects on Fluorescent Tracer Concentration Measurement

To ensure an accurate evaluation of pesticide spray application efficiency and pesticide mixture uniformity, reliable and accurate measurements of fluorescence concentrations in spray solutions are critical. The objectives of this research were to examine the effects of solution temperature on measured concentrations of fluorescent tracers as the simulated pesticides and to develop models to correct the deviation of measurements caused by temperature variations. Fluorescent tracers (Brilliant Sulfaflavine (BSF), Eosin, Fluorescein sodium salt) were selected for tests with the solution temperatures ranging from 10.0 °C to 45.0 °C. The results showed that the measured concentrations of BSF decreased as the solution temperature increased, and the decrement rate was high at the beginning and then slowed down and tended to become constant. In contrast, the concentrations of Eosin decreased slowly at the beginning and then noticeably increased as temperatures increased. On the other hand, the concentrations of Fluorescein sodium salt had little variations with its solution temperature. To ensure the measurement accuracy, correction models were developed using the response surface methodology to numerically correct the measured concentration errors due to variations with the solution temperature. Corrected concentrations using the models agreed well with the actual concentrations, and the overall relative errors were reduced from 42.36% to 2.91% for BSF, 11.72% to 1.55% for Eosin, and 2.68% to 1.17% for Fluorescein sodium salt. Thus, this approach can be used to improve pesticide sprayer performances by accurately quantifying droplet deposits on target crops and off-target areas.

Experimental Investigation on Rotordynamic Characteristics and Rotor System Stability of a Novel Negative Dislocated Seal

Air-induced force generated in seals is one key factor on the stability of the rotor system. In this paper, a novel negative dislocated seal (NDS) was developed in respect of dislocated bearing theory, to reduce hydrodynamic pressure effect and air-induced force and improve rotor stability as well. A test rig was built to test rotordynamic characteristics and rotor stability of the NDS. The rotordynamic characteristics of seals were investigated based on the unbalanced synchronous excitation method, and seal-rotor system stability was evaluated by the identification method with an electromagnetic bearing exciter. The effects of both rotating speed and inlet/outlet pressure ratio on the rotordynamic characteristics and rotor stability of both NDS and conventional cylindrical labyrinth seal were experimentally investigated. The results show that with the increasing rotating speed, inlet/outlet pressure ratio is promising to reduce the direct stiffness coefficients of seals and the logarithmic decrement rate of seal-rotor system and enhance both cross stiffness and damping coefficient as well. Besides, the developed NDS effectively reduces cross-stiffness coefficients and increases direct damping coefficients and the logarithmic decrement rate of the seal-rotor system, relative to the conventional cylindrical seal. The proposed seal can effectively improve seal stability of turbomachinery.

Correction of UVS-AB-T UV Radiometers Using a Radiative Transfer Model

Observation of UV radiation is of major importance to human health and to the calculation of photochemical reaction rates. However, the sensitivity of UV radiometers decays because of equipment aging. A correction method is therefore proposed by using a decrement formula that is approximately a quadratic function of time and is obtained by fitting the clear-sky observation data from an aged UVS-AB-T UV radiometer with the data simulated by the Tropospheric Ultraviolet and Visible (TUV) radiative transfer model. The corrected data from the older radiometer are verified by the data from another newer radiometer on selected clear-sky days. The results show a high correlation and a low bias between the radiometers, and the mean of the corrected data from the older radiometer is 94.5% of that from the newer radiometer. After a long time of use, the decrement of the observation data would increase dramatically and errors of the data after correction would still be significant. In Dongguan, China, a recommendation is made that a UV radiometer should not be used for more than 5 years when the decrement rate reaches 50%.

Study of the Pretreatment and Disperse Dyeing Process for the PLA/cotton Blended Fabric: High Physical Resistance and Dyeing Performance

In this paper, the optimal pretreatment and disperse dyeing process for the novel PLA/cotton blended fabric was studied. In the pretreatment stage, enzyme and H2O2 were applied to test their effect on the decrement-rate and bending length. After pretreatment, the PLA component of this fabric was dyed with three different disperse dyes and the effect of dyeing parameters including time, temperature and pH on the K/S value and tear strength were studied. Besides, DSC and SEM were also applied to analyze this pretreatment and dyeing process. The recommended pretreatment and disperse dyeing conditions were summarized.

Characteristics of Combined Sewer Overflows in Nanjing and Selection of Intercepted Time

The purpose of this study is to investigate the characteristic of pollutants overflow on storm events, relationships between pollutant load and rainfall duration, and rainfall intensity in Chaotian Palace, Nanjing City. The results showed that high pollutant concentrations were observed in the initial stage of runoff and decreased continuously over rainfall duration. Moreover, the wash off ratios of pollutants load decreased with rainfall intensity declining. Furthermore, initial 5, 10, 20, 30, 40 min intervals of a rainfall event were chosen to investigate the variation of pollutants load decrement rate of CSOs. An obvious corner at initial 10 min was observed for all parameters in whole storm events. The slope of curves before 10 min is steeper than after that one. Based on the analysis on pollutants load decrement rate of CSOs, 10 min could be chosen as control point in intercepted engineering for optimizing treatment facilities in order to achieve cost-effective CSOs control.

The Security Study of Train Derailment on High-Speed Railway Bridge

In this paper vehicle-bridge coupling system is divided into vehicle system and bridge system. The equations of vehicle vibration and bridge vibration are solved in numerical method, considered the displacement of wheel and rail as convergence criterion. The security of running train is studied on the hand of wheel-rail force, derailment coefficient, load decrement rate of wheel weight, and the reason of train derailing on high-speed railway bridge is analyzed. By the example of multiple span simple supported beam bridge, the result derived by this method is proved that the bridge meet train security and amenity requirement.

Water Remediation Using Pulsed Power Discharge under Water with an Advanced Oxidation Process

In the present study, the degradation of organic contaminants by streamer discharge using a pulsed power generator under water is investigated. The experiments are conducted based on the decolorization of two dyes, Acid Red 1 and Acid Blue 74, and the decomposition of 1,4-dioxane. A gas-liquid separated reactor is developed and employed to achieve degradation with high energy efficiency. A tungsten wire electrode is placed in the gas phase, and a grounded 316 stainless steel wire is immersed in the water. The pulsed high voltage is generated by a magnetic pulse compression circuit and is applied to the wire electrode to generate streamer discharges in the gas region, which propagate into the bubble injected into the water. Oxygen and argon gases are injected to identify the dominant reactions of the degradation of organic contaminants. Acid Red 1 and Acid Blue 74 solutions are successfully decolorized by the discharges. The ozone produced by discharges in the gas region primarily decolorizes the dye solutions. The total organic carbon (TOC) of the 1,4-dioxane solution decreases due to discharge when argon is injected. The decrement rate of TOC does not increase through gaseous ozone injection or by discharges in the case of oxygen injection. These results show that the chemical species produced by discharges and by chemical reactions in the solution, such as hydroxyl and hydroperoxyl radicals, primarily decompose 1,4-dioxane. Iron ions dissolved by electrolysis enhanced the TOC decrement rate according to the Fenton reaction in acidic conditions.