The Effect of a High-Frequency-Hearing-Threshold Weighted Value on the Diagnosis of Occupational-Noise-Induced Deafness

Objective: In order to provide a theoretical basis for the revision of the current diagnostic criteria for occupational noise-induced deafness (ONID), we evaluated the degree of ONID by analyzing different high-frequency-hearing- threshold-weighted values (HFTWVs). Methods: A retrospective study was conducted to evaluate the diagnosis of patients with ONID from January 2016 to January 2017 in Guangdong province, China. Based on 3 hearing tests (each interval between the tests was greater than 3 days), the minimum threshold value of each frequency was obtained using the 2007 edition’s diagnostic criteria for ONID. The speech frequency and the HFTWVs were analyzed based on age, noise exposure, and diagnostic classi-fication using SPSS21.0. Results: 168 patients in total were involved in this study, 154 males and 14 females, and the average age was 41.18 ± 6.07. The diagnosis rate was increased by the weighted value of the high frequencies and was more than the mean value of the pure speech frequency (MVPSF). The diagnosis rate for the weighted 4 kHz frequency level increased by 13.69% (χ2 = 9.880, P = 0.002), the weighted 6 kHz level increased by 15.47% (χ2 = 9.985, P = 0.002), and the weighted 4 kHz + 6 kHz level increased by 15.47% (χ2 = 9.985, P = 0.002). The differences were all statistically significant. The diagnostic rate of the different thresholds showed no obvious difference between the genders. The age groups were divided into less than or equal to 40 years old (group A) and 40 - 50 years old (group B). There were several groups with a high frequency: high frequency weighted 4 kHz ( group A χ2 = 3.380, P = 0.050;group B χ2 = 4.054, P = 0.032), high frequency weighted 6 kHz (group A χ2 = 6.362, P = 0.012;group B χ2 = 4.054, P = 0.032), weighted 4 kHz + 6 kHz (group A χ2 = 6.362 P = 0.012;B χ2 = 4.054, P = 0.032) than those of MVPSF in the same group on ONID diagnosis rate. The differences between the groups were statistically significant. There was no significant difference between the age groups (χ2 = 2.265, P = 0.944). The better ear’s (the smaller hearing threshold weighted value) MVPSF and the weighted values for the different high frequencies were examined in light of the number of working years;the group that was exposed to noise for more than 10 years had significantly higher values than those of the average thresholds of each frequency band in the groups with 3 - 5 years of exposure (F = 2.271, P = 0.001) and 6 - 10 years of exposure (F = 1.563, P = 0.046). The differences were statistically significant. The different HFTWVs were higher than those of the MVPSF values, and the high frequency weighted 4 kHz + 6 kHz level showed the greatest difference, with an average increase of 2.83 dB. The diagnostic rate that included the weighted high frequency values was higher for the mild, moderate, and severe cases than those patients who were only screened with the pure frequency tests. The results of the comparisons of the diagnosis rates for mild ONID were as follows: the weighted 3 kHz high frequency level (χ2 = 3.117, P = 0.077) had no significant difference, but the weighted 4 kHz level (χ2 = 10.835, P = 0.001), 6 kHz level (χ2 = 9.985, P = 0.002), 3 kHz + 4 kHz level (χ2 = 6.315, P = 0.012), 3 kHz + 6 kHz level (χ2 = 6.315, P = 0.012), 4 kHz + 6 kHz level (χ2 = 9.985, P = 0.002), and 3 kHz + 4 kHz + 6 kHz level (χ2 = 7.667, P = 0.002) were significantly higher than the diagnosis rate of the mean value of the PSF. There was no significant difference between the 2 groups for the moderate and severe grades (P > 0.05). Conclusion: Different HFTWVs increase the diagnostic rate of ONID. The weighted 4 kHz, 6 kHz, and 4 kHz + 6 kHz high frequency values greatly affected the diagnostic results, and the weighted 4 kHz + 6 kHz high frequency hearing threshold value has the maximum the effect on the ONID diagnosis results.

β-BaB_(2)O_(4) with special cut-angle applied to single crystal cascaded third-harmonic generation

High-efficiency single crystal cascaded third-harmonic generation(THG)was realized inβ-BaB_(2)O_(4)(BBO)material with special cut-angle.By analyzing effective nonlinear optical coefficient(d_(eff))of the cascaded THG process,which was composed by type-II frequency doubling and type-I sum-frequency,the optimum phase matching(PM)direction in BBO crystal was determined to be(θ=32.1°,φ=11°).With an optimized 9-mm long sample which was processed along this direction,the highest cascaded THG conversion efficiency reached 42.3%,which is much superior to the similar components reported previously,including ADP,KDP,and Gd_(x)Y_(1-x)COB crystals.

Theoretical Study on the Characteristics of Atmospheric Radio Frequency Discharges by Altering Electrode Gap

In this paper, we present a theoretical study on the discharge characteristics of radio-frequency discharges at atmospheric pressure driven by a higher frequency of 40.68 MHz while the electrode gap is altered. Based on the analytical equations and simulation data from a one-dimensional fluid model, an optimal gap between electrodes, at which the largest electron density is obtained, can be observed under a constant power condition; however, as the electrode gap increases the time-averaged electron temperature decreases, and the underpinning physics is also discussed based on the simulation results. This study indicates that at a constant power by choosing an appropriate electrode spacing, the rf discharge can be effectively optimized at atmospheric pressure.

A GaAs planar Schottky varactor diode for left-handed nonlinear transmission line applications

The left-handed nonlinear transmission line （LH-NLTL） based on monolithic microwave integrated circuit （MMIC） technology possesses significant advantages such as wide frequency band, high operating frequency, high conversion efficiency, and applications in millimeter and submillimeter wave frequency multiplier. The planar Schottky varactor diode （PSVD） is a major limitation to the performance of the LH-NLTL frequency multiplier as a nonlinear component. The design and the fabrication of the diode for such an application are presented. An accurate large-signal model of the diode is proposed. A 16 GHz-39,6 GHz LH NLTL frequency doubler using our large-signal model is reported for the first time. The measured maximum output powers of the 2nd harmonic are up to 8 dBm at 26.4 GHz, and above 0 dBm from 16 GHz to 39.6 GHz when the input power is 20 dBm. The application of the LH-NLTL frequency doubler furthermore validates the accuracy of the large-signal model of the PSVD.

New Precoded Spatial-Multiplexing for an Erasure Event in Single Frequency Networks

In this paper, we propose a new spatial-multiplexing(SM) scheme employing an orthogonal precoder over Rayleigh-fading channels for an erasure event in single frequency networks(SFN). To optimize the precoder, the average bit error rate(BER) is evaluated and minimized through a mathematical analysis. Compared to an ordinary SM, the proposed scheme guarantees identical BER performance under non-erasure fading channels and achieves a greatly improved performance under erasure fading channels, especially for a higher erasure-ratio and SNR values. This improvement is mainly due to the increase in the diversity gain incurred by the optimized precoder over the erasure event. We also compare the performance of the proposed SM to that of the conventional constellation-rotation(CR) scheme applied to the single antenna SFN systems. The results of a computer simulation show that the performance of the new scheme is more effective than that of a conventional CR across all simulation cases.

Globally accurate ab initio based potential energy surface of H_2O^+(X^4A'')

A globally accurate potential energy surface is reported for the electronic ground-state H2O＋. The ab initio energies utilized to map the potential energy surface are calculated at the multireference configuration interaction method employing the aug-cc-pVQZ basis set and the full valence complete active space wave function as reference. In order to improve accu- racy of the resulting raw ab initio energies, they are then extrapolated to the complete basis set limit and most importantly to the full configuration-interaction limit by semiempirically correcting the dynamical correlation using the double many- body expansion-scaled external correlation method. The topographical features of the current potential energy surface were examined in detail, which agree nicely with those of other theoretical work.

Energy distributions of the large-scale horizontal currents caused by wind in the baroclinic ocean

Ocean current data for nearly 3 months in the South China Sea (SCS), combined with the NCEP/NCAR reanalysis wind data, are analyzed. The results indicate that the wind en-ergy enters the upper mixed layer in a wide continuous frequency band. In addition, the interac-tion between the low-frequency wind anomaly and the low-frequency current anomaly is the most ‘effective’ way for the energy input from the wind to the upper ocean. However, only the inertial and the near inertial energy propagate downwards through the upper mixed layer. The down-ward-propagating energy is distributed into the barotropic currents, the baroclinic currents and each mode of the baroclinic currents following the normal distributions. The energy change ratios between the barotropic motion to the baroclinic motion induced by the wind present a normal distribution of N (0.0242, 0.3947). The energy change ratios of the first 4 baroclinic modes to the whole baroclinic currents also follow the normal distributions. The first baroclinic mode follows N (0.2628, 0.1872), the second N (0.1979, 0.1504), the third N (0.1331, 0.1633), and the fourth N (0.0650, 0.1540), respectively.

Microwave peak absorption frequency of liquid

Microwave-assisted extraction is a new effective method which has practical ap-plications in many fields. Microwave heating is one of its physical mechanisms,and it also has the characteristic of selectivity. When the applied microwave fre-quency equals a certain absorption frequency of the material (or specific compo-nent),the material will intensively absorb microwave energy. This is also known as resonant absorption,and the frequency is called the peak absorption frequency which depends on the physical structure of the material. In this work,dynamic hy-drogen bond energy was included in molecular activation energy; with the liquid cell model,the expression of interaction energy between dipolar molecules was derived. The rotational relaxation time was gotten from the Eyring viscosity formula. Then based on the relationship between dielectric dissipation coefficient and re-laxation time,the expression of microwave peak absorption frequency as a func-tion of the material physical structure,rotational inertia and electrical dipole mo-ment of molecules was established. These theoretical formulas were applied to water and benzene,and the calculated results agree fairly well with the experi-mental data. This work can not only deepen the study of the interaction between microwave and material,but also provide a possible guide for the experiment of microwave-assisted extraction.

70-nm-gated InAlN/GaN HEMTs grown on SiC substrate with f_T/f_(max)>160GHz

lnA1N/GaN high-electron-mobility transistors （HEMTs） on SiC substrate were fabricated and character- ized. Several techniques, consisting of high electron density, 70 nm T-shaped gate, low ohmic contacts and a short drain-source distance, are integrated to gain high device performance. The fabricated InA1N/GaN HEMTs exhibit a maximum drain saturation current density of 1.65 A/ram at Vgs = 1 V and a maximum peak transconductance of 382 mS/rnm. In addition, a unity current gain cut-off frequency （fT） of 162 GHz and a maximum oscillation frequency （fmax） of 176 GHz are achieved on the devices with the 70 nm gate length.