A Discovery of Resonance Frequencies on Twelve Meridians of Human Body by Bioimpedance Spectroscopy Method

Objective: The resonance frequency (Fr) of twelve meridians was observed by means of sweep frequency of weak constant current, and a method of evaluating Fr was explored. Method: Four-electrode bioimpedance spectroscopy was used in the study. Constant current of 1~100Hz was applied from a phase-locked amplifier through the excitation electrode to the twelve meridians of 30 healthy subjects. Data were collected by the test electrode and the Fr of the twelve meridians was obtained by data fitting in Matlab. <br>Result: Among the twelve meridians, the Fr of the small intestine meridian is the lowest, and the gallbladder meridian is the highest, which are 23.18±0.99Hz and 28.27±1.39 Hz, respectively. The mean resonance frequencies of meridians of the same name on hand and foot are 24.80±1.34Hz and 26.22±1.17Hz, respectively. The Fr of the Shao Yin meridian of the hands and feet is basically equal, the other five pairs of foot meridians are all higher than the hand meridian, and the difference of the Yang meridian of the same name is greater than the Yin meridian of the same name, the Fr of hand Shao Yang meridian, hand Tai Yang meridian and hand Yang Ming meridian were lower than those of foot meridians. The mean value of 6 pairs of yin and yang meridians are 25.59 ± 1.97Hz and 25.42 ± 0.70Hz, respectively. <br>Conclusion: The resonance frequencies of the twelve meridians ranged from 23 to 28Hz approximately.

The Effect of Test, Electrode, and Rate on Electrocochleography Measures

Electrocochleography (ECochG) is the measurement of stimulus-related cochlear potentials and the compound action potential (AP). Its primary clinical application is with the assessment of inner ear disorders. There are few studies examining the variability of ECochG measures.The objective of the study was to examine the effect of test (i.e., initial versus retest), electrode (i.e., extratympanic versus tympanic), and stimulus rate (i.e., 7.7 versus 77.7/sec) on ECochG indices (i.e., summating potential [SP] amplitude, AP latency, AP amplitude, SP/AP amplitude ratio, and SP/AP area ratio).Correlational and three-factor repeated measures designs were employed.Eighteen normal-hearing young adults participated.ECochG responses were obtained with 90 dB nHL click stimuli for an initial test and retest at two stimulus rates with a commercially available extratympanic (TIPtrode™) and tympanic (Lilly TM-Wick) electrode. Separate repeated measures linear mixed-model analysis of variance examined the effect of test, electrode, and rate for all ECochG indices. Test–retest variability was also examined with correlation analyses; an examination of mean test–retest differences and their 95% confidence intervals (CI); and construction of Bland-Altman plots.The presence of SP and AP responses varied across experimental conditions. Electrode and rate were statistically significant predictors (p < 0.05) of SP and AP responses: SP and AP responses were more likely to be present with the tympanic electrode and at the slow rate. Statistically significant correlations (p < 0.05) were found between initial tests and retests with all ECochG indices with both electrodes with the exception of SP amplitude with the TIPtrode™ electrode. There were no significant main effects of test (initial versus retest) or interactions of test and electrode or rate for any of the ECochG indices (p > 0.05). The 95% CI of the mean test–retest differences contained 0 confirming that the effect of test was not statistically significant. There was a statistically significant main effect of electrode (p < 0.05) on three ECochG measures. The Lilly TM-Wick electrode produced larger SP amplitudes, AP amplitudes, and SP/AP area ratios than TIPtrode™ electrodes. A statistically significant main effect of rate (p < 0.05) was identified for all ECochG measures. The effect of rate on AP latency and amplitude was expected. Increasing the stimulus rate prolonged the AP latency and decreased AP amplitude. SP amplitude was larger for the faster rate.There was no difference between electrodes with regard to test–retest measures. However, considering the higher likelihood of ECochG SP and AP responses and larger SP amplitude, SP/AP amplitude ratio, and SP/AP area ratio indices, the tympanic electrode placement is recommended for clinical practice. The addition of a fast stimulus rate may be considered for enhanced SP amplitude, SP/AP amplitude ratio, and SP/AP area ratio albeit with the consideration of the loss of SP and AP responses in some individuals.

Characterization of an Electrodynamic Dust Shield Device for PV Panel Soiling Mitigation

In this study, prototype electrodynamic dust shield (EDS) devices large enough to cover commercial photovoltaic (PV) modules were fabricated and tested in the lab and in the field. The EDS device consisted a polyethylene terephthalate (PET) substrate with screen-printed silver electrodes, and a PET cover sheet that bonded to the substrate using a synthetic rubber adhesive. The voltage-current characteristics of the EDS device was measured while square wave high voltage was applied to the device, so as to determine the power consumption of the EDS device. The EDS device was also tested in the field to determine its effectiveness in soiling mitigation. Measurements showed that the EDS capacitance varied from approximately 600 pF in the air-conditioned lab to 2 nF in the field when the EDS device temperature reached 45 °C. The variation of the capacitance has significant relevance to the capacity requirements for the high voltage sources needed to energize the EDS device and its power consumption. Under laboratory conditions, the EDS power consumption was found to be 0.3 W m−2 at 6 kVp-p and 1 Hz, and roughly proportional to the voltage squared. In the field test electrode damage was observed, due to electrical discharge at the electrode lines. As a result, the EDS operation did not show significant effect of soiling mitigation. The results of this study are useful for designing high voltage sources for EDS operation, and for modifying the design and fabrication methods in order to produce EDS devices that can effectively repel dust in the field.

Effect of Deposit Composition on the Mechanical Properties and Cracking Tendency of Cellulosic-Covered SMAW Weld Deposits

This investigation utilizes test electrodes manufactured with boron at different levels (including no boron). The design of these electrodes is identical with the exception of the intentional changes highlighted. Gapped bead on plate (GBOP) testing is used to determine the relative propensity of the electrodes for weld metal cracking. Test electrodes are also evaluated for deposit composition, CVN impact toughness, strength, and hardness on pipe joints. This work also uses a non boron-containing test electrode whose deposit composition has been modified such that its carbon equivalent is the same as one of the boron-containing electrodes. This serves to separate the influence of the specific element boron from the influence of general carbon equivalent/hardenability on the tendency for cracking. The results indicate that the effect of changes in boron and carbon equivalent over the range tested and in this specific electrode design is very slight. In most cases, the effect is not significant when compared to the amount of variation observed in the testing. In essence, the signal was lost in the noise. In terms of susceptibility to hydrogen assisted cold cracking (HACC) — the area of most concern — there appear to be other factors that are much more influential than those tested. If the goal is to minimize the cracking sensitivity of cellulosic weld metal, simply eliminating the use of boron is not the answer. More work is required to identify these other factors and quantify their effect.