Reducing industrial noise by the use of damping alloys when manufacturing mining equipment parts.

The existing experience of noise and vibration specialists has shown that the problem of noise reduction is very relevant, especially for the mining industry. Traditional methods of dealing with industrial noise are not effective enough. In solving this issue, it is advisable to reduce the noise level at the source of its occurrence through the use of metal alloys with enhanced dissipative properties. The article presents the results of experimental studies of developing steels with increased damping properties for manufacturing perforator parts: bit bodies and drill rods. In this article, the sound pressure level of alloys dependence on the type of heat treatment has been studied, and the optimal content of alloying elements has been established to ensure the development of the ferrite-pearlite structure. This structure is characterized by an increased dislocation density and is the reason for reducing the noise of the drill rod and the body of the perforator bit by 10-12 dB A. In addition, the article establishes the pattern of noise intensity at different frequency intervals for standard and developed alloys.

Stochastic sensitivity analysis and feedback control of noise-induced transitions in a predator-prey model with anti-predator behavior.

In this study, we investigate a stochastic predator-prey model with anti-predator behavior. We first analyze the noise-induced transition from a coexistence state to the prey-only equilibrium by using the stochastic sensitive function technique. The critical noise intensity for the occurrence of state switching is estimated by constructing confidence ellipses and confidence bands, respectively, for the coexistence the equilibrium and limit cycle. We then study how to suppress the noise-induced transition by using two different feedback control methods to stabilize the biomass at the attraction region of the coexistence equilibrium and the coexistence limit cycle, respectively. Our research indicates that compared with the prey population, the predators appear more vulnerable and prone to extinction in the presence of environmental noise, but it can be prevented by taking some appropriate feedback control strategies.

Prevalence of tinnitus in noise-exposed workers and its influencing factors / 环境与职业医学

Background Tinnitus is a common symptom in workers exposed to noise, and no specific treatment is available yet. Paying attention to the influencing factors of tinnitus is very important to prevent tinnitus. Objective To investigate the situation of tinnitus among noise-exposed workers and its influencing factors. Methods Using a cross-sectional study design, 1011 noise-exposed male workers in Hangzhou were studied. Tinnitus status, age, education, personal protection, smoking history, drinking history, and family history of the participants were surveyed by questionnaires. Binaural pure tone hearing threshold test was performed on all study subjects. The environmental noise in the workplace was measured. The relationships of tinnitus with noise exposure intensity, noise exposure time, noise exposure category, cumulative noise exposure, and wearing hearing protectors among the noise-exposed workers were analyzed by logistic regression. Results The prevalence of tinnitus among the noise-exposed workers was 36.1%. The mean hearing thresholds at 500, 3000, 4000, and 6000 Hz in the right and left ears were higher in the tinnitus group than in the non-tinnitus group (P<0.05); the hearing threshold at 2000 Hz in the right ear was higher in the tinnitus group than in the non-tinnitus group (P<0.05). There was no statistically significant difference between the two groups in the prevalence of monaural speech-frequency hearing loss or monaural high-frequency hearing loss (P>0.05). The on-site noise intensity was divided into three groups: ＜85, 85-＜95, and ≥95 dB(A); the prevalence of tinnitus in the three groups was 19.6%, 40.5%, and 66.7% respectively. The years of noise exposure was divided into three groups: ＜1, 1-＜5, and ≥5 years; the prevalence of tinnitus in the three groups was 17.9%, 34.0%, and 45.4% respectively. The cumulative noise exposure was divided into six groups: ＜80, 80-＜85, 85-＜90, 90-＜95, 95-＜100, and ≥100 dB(A)·year; the prevalence of tinnitus in the six groups was 6.8%, 25.0%, 31.0%, 39.6%, 43.1%, and 46.7% respectively. The prevalence of tinnitus was higher in the non-stationary noise group (42.5%) than in the stationary noise group (26.8%) (χ2=26.18, P<0.01), and the prevalence in the group without or with hearing protection was 39.7% and 35.5% respectively. The results of logistic regression showed that workers exposed to higher intensity, longer noise exposure, higher cumulative noise exposure, and non-stationary noise (reference: stationary noise) resulted in a higher risk of tinnitus (Ptrend<0.01 or P<0.01); workers wearing of hearing protection device versus those not showed a lower risk of tinnitus (P<0.05). Conclusion Higher intensity, longer exposure to noise, and more cumulative noise exposure associate with a higher risk of tinnitus. Wearing hearing protective device can reduce the risk of tinnitus. Tinnitus in noise-exposed workers can precede the presentation of abnormal hearing loss.

Factors affecting high-frequency hearing loss among noise-exposed workers in an automobile manufacturing company / 环境与职业医学

Background The influencing factors of noise hazards in the automotive manufacturing industry are complex, diverse, and mutually correlated, resulting in significant health impacts on workers. Objective To explore the application of generalized estimating equations (GEE) to analyze the factors affecting high-frequency hearing loss among noise-exposed workers in an automotive manufacturing company, guiding enterprises to scientifically carry out employee hearing protection programs. Methods The data of occupational health field evaluation and occupational health surveillance of an automobile manufacturing company for five consecutive years from 2018 to 2022 were collected, and 806 noise-exposed workers with pure tone hearing test results for all five consecutive years were selected as study participants. The retrieved indicators were gender, physical examination year, noise intensity, blood pressure, white blood cell counts, red blood cell counts, platelet counts, concentrations of hemoglobin, alanine transaminase, aspartate aminotransferase, smoking, drinking, etc. Gender, noise intensity, blood pressure, white blood cell counts, red blood cell counts, concentrations of hemoglobin, platelet counts, glutamate aminotransferase, glutamate aminotransferase, smoking, and drinking were set as independent variables, and occurrence of high-frequency hearing loss was set as a dependent variable, and GEE were constructed by using the statistical software of SPSS 20.0 to analyze the influencing factors of high-frequency hearing loss. Results Of the 806 workers, 698 were male (86.6%) and 108 were female (13.4%). The detection rates of high-frequency hearing loss in each year from 2018 to 2022 were 66.4% (535/806), 69.8% (563/806), 70.0% (564/806), 68.9% (555/806), and 68.2% (550/806), respectively. The detection rate of high-frequency hearing loss in the company was varied significantly by gender, lowered white blood cell counts, lowered red blood cell counts, lowered platelet counts, smoking, and drinking (P<0.05). The results of GEE analysis showed that after adjusting for selected confounding factors and excluding interaction effects, the risk of high-frequency hearing loss was higher in men than in women (P=0.001; OR=1.907, 95%CI: 1.286, 2.829); it was higher in workplace with disqualified noise intensity than in those without (P=0.043; OR=1.289, 95%CI: 1.009, 1.648); it was also higher in smokers than in non-smokers (P=0.004; OR=1.507, 95%CI: 1.137, 1.999). Conclusion Gender, noise intensity, and smoking are the main influencing factors of high-frequency hearing loss in noise-exposed workers in this automobile manufacturing company. Controlling smoking and reducing noise exposure intensity may reduce the occurrence of high-frequency hearing loss in workers.

[Investigation and analysis of underground noise in Sichuan coal mines].

Objective: To understand the harm degree of underground noise and provide basis for noise control. Methods: In November 2019, 13 typical coal mines in Sichuan Province were selected as the research objects, and a total of 1203 sites and 609 jobs of noise exposure were investigated. Results: The noise intensity P75 >80 dB (A) was measured. The noise intensity of the inspection place of the air compressor is >86 dB (A) , the noise intensity of the inspection place of the gas drainage and the operation place of the main fan is between 80-85 dB (A) . Conclusion: Besides the harm of dust, noise exposure should also be paid attention to, and the measures of sound absorption and sound insulation should be taken or personal protection should be strengthened.

Investigation and analysis of underground noise in Sichuan coal mines / 中华劳动卫生职业病杂志

Objective: To understand the harm degree of underground noise and provide basis for noise control. Methods: In November 2019, 13 typical coal mines in Sichuan Province were selected as the research objects, and a total of 1203 sites and 609 jobs of noise exposure were investigated. Results: The noise intensity P75 >80 dB (A) was measured. The noise intensity of the inspection place of the air compressor is >86 dB (A) , the noise intensity of the inspection place of the gas drainage and the operation place of the main fan is between 80-85 dB (A) . Conclusion: Besides the harm of dust, noise exposure should also be paid attention to, and the measures of sound absorption and sound insulation should be taken or personal protection should be strengthened.

Characterizing ISI and sub-threshold membrane potential distributions: Ensemble of IF neurons with random squared-noise intensity.

A theoretical investigation is presented that characterizes the emerging sub-threshold membrane potential and inter-spike interval (ISI) distributions of an ensemble of IF neurons that group together and fire together. The squared-noise intensity σ2 of the ensemble of neurons is treated as a random variable to account for the electrophysiological variations across population of nearly identical neurons. Employing superstatistical framework, both ISI distribution and sub-threshold membrane potential distribution of neuronal ensemble are obtained in terms of generalized K-distribution. The resulting distributions exhibit asymptotic behavior akin to stretched exponential family. Extensive simulations of the underlying SDE with random σ2 are carried out. The results are found to be in excellent agreement with the analytical results. The analysis has been extended to cover the case corresponding to independent random fluctuations in drift in addition to random squared-noise intensity. The novelty of the proposed analytical investigation for the ensemble of IF neurons is that it yields closed form expressions of probability distributions in terms of generalized K-distribution. Based on a record of spiking activity of thousands of neurons, the findings of the proposed model are validated. The squared-noise intensity σ2 of identified neurons from the data is found to follow gamma distribution. The proposed generalized K-distribution is found to be in excellent agreement with that of empirically obtained ISI distribution of neuronal ensemble.

State estimation for a class of artificial neural networks with stochastically corrupted measurements under Round-Robin protocol.

This paper is concerned with the state estimation problem for a class of artificial neural networks (ANNs) without the assumptions of monotonicity or differentiability of the activation functions. The measured outputs are corrupted by stochastic noise signal whose intensity is quantified by a nonlinear function. In order to accommodate the bandwidth limit of the communication channel between the ANN and the state estimator, an equal allocation scheme (i.e. Round-Robin protocol) of the communication resource is employed to effectively mitigate data congestions and save energies. A set of zero-order holders (ZOHs) is utilized to store the received measurements, such that the utilization of the received measurements can be maximized. An update matrix approach is developed to handle the time-varying yet periodic time-delays resulting from the adoption of the Round-Robin protocol. The aim of the proposed problem is to design a state estimator such that the error dynamics is exponentially ultimately bounded. A combination of the Lyapunov stability theory and the stochastic analysis technique is used to derive some easy-to-test conditions for the existence of the desired state estimator. The estimator gains are characterized by the solution to a convex optimization problem that is solved via the semi-definite programme method. Simulation results are given to demonstrate the effectiveness of the proposed estimation approach.