Effect of mixed magnetic field on physical properties of atmospheric suspended fine particles.

In recent years, the fine particles suspended in the atmosphere, especially the particle size less than 10 µ m , have caused very adverse effects on the climate environment and human health. However, the current research on the causes of air pollution mainly focuses on human activities and weather conditions. Considering the weak magnetism and chargeability of atmospheric fine particles, this study proposed a new view that space electromagnetic radiation may affect the physical properties of fine particles. We first analyzed the dynamic characteristics of magnetic micro-particle in the electromagnetic environment, and built a simulation model in the COMSOL simulation software. Finally, based on the theoretical analysis and simulation results, we built an experimental verification system to evaluate the effects of electromagnetic radiation on the physical properties of micro-particle, and carried out a 30-day control experiment. The experimental results showed that the physical properties such as particle size distribution, mass concentration, and morphology of suspended fine particles in the atmosphere under electromagnetic radiation are significantly different from those under non-electromagnetic radiation environment. It can be inferred that the aggregation, fusion, and deposition of suspended particles in the atmosphere are closely related to the complex electromagnetic environment in space.

Development of a Transient Magnetic Field Sensor Based on Digital Integration and Frequency Equalization.

Transient magnetic field sensors are used in various electromagnetic environment measurement scenarios. In this paper, a novel magnetic field sensor based on a digital integrator was developed. The antenna was a small B-DOT loop. It was designed optimally for the simulation. The magnetic field signal was digitally integrated with the improved Al-Alaoui algorithm, resulting in less integration error. To compensate for the bandwidth loss of the optical fiber system, we specially designed an FIR (finite impulse response) filter for frequency compensation. The circuit was described, and the transimpedance amplifier was specially designed to ensure the low noise characteristic of the receiver. The sensitivity of the sensor was calibrated at 68.2 A·m-1/mV, the dynamic range was 50 dB (1-300 kA/m), the linear correlation coefficient was 0.96, and the bandwidth was greater than 100 MHz. It was tested and verified under the action of an A-type lightning current. The sensor exhibited high-precision performance and flat amplitude-frequency characteristics. Therefore, it is suitable for lightning positioning, partial discharge testing, electromagnetic compatibility management, and other applications.

Effects of long-term exposure to strong electromagnetic radiation environment on the peripheral complete blood cells of operators / 解放军医学杂志

Objective To observe the effects of long-term exposure to strong electromagnetic environment on the peripheral complete blood cells of the operators. Methods A total of 239 male workers engaged in strong electromagnetic radiation operation for at least 1 year were consecutively raised between April and October 2019 as the exposed group, and 203 male workers no-exposed to strong electromagnetic equipment were raised as non-exposed group. Multipoint measurements were done of electromagnetic frequency and power density in electromagnetic radiation operation area, the differences of blood routine indexes between the exposed group and non-exposed group were compared, and the variation trend of difference index with increased exposure years was analyzed. Results No significant difference existed between the two groups in age, gender, work experience and body mass index (BMI). The electromagnetic frequency band in the operation area was between 5.5-2000 MHz, the maximum power density could reach up to 14 W/m2in the shielding point, and reach up to 535.17 W/m2in the open area. Compared with the non-exposed group, the levels of mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC) and mean platelet volume (MPV) were significantly elevated (P<0.05), while the red blood cell count (RBC) and haematocrit (HCT) was markedly reduced (P<0.05) in the exposed group. With the prolongation of the exposure time, the levels of RBC and HCT were relatively stable, but MCH, MCHC and MPV showed fluctuation from higher to lower level. Conclusions Long-term exposure to strong electromagnetic environment may lead to lower levels of red blood cells in related workers. Compensation may be achieved through hemoglobin elevation at early stage, which nevertheless weakens through hemoglobin reduction during the exposure time prolonged.

Planning principles analysis of 7T MRI room / 医疗卫生装备

Objective To draw up a plan for 7T MRI room based on analyzing its features.Methods 3T and 7T MRI machines were compared from the aspects of weight,installation,transport space requirement,dynamic interference and magnetic field distribution.The data related to 7T MRI were studied to plan the room rationally.Results When compared with 3T MRI,7T MRI had the weight increased by 4 to 6 times,the volume raised by 30％,more dynamic interference and irregular magnetic field distribution.The ground bearing of 7T room was higher than 40 t,the minimum installation space was larger than 54 m2,and shielding was executed by ferro-magnetic structure internally and by radio externally.Conclusion 7T MRI poses high requirements on the room,and plans have to be made at advance.

Planning principles analysis of 7T MRI room / 医疗卫生装备

Objective To draw up a plan for 7T MRI room based on analyzing its features.Methods 3T and 7T MRI machines were compared from the aspects of weight,installation,transport space requirement,dynamic interference and magnetic field distribution.The data related to 7T MRI were studied to plan the room rationally.Results When compared with 3T MRI,7T MRI had the weight increased by 4 to 6 times,the volume raised by 30％,more dynamic interference and irregular magnetic field distribution.The ground bearing of 7T room was higher than 40 t,the minimum installation space was larger than 54 m2,and shielding was executed by ferro-magnetic structure internally and by radio externally.Conclusion 7T MRI poses high requirements on the room,and plans have to be made at advance.

Evaluación del ambiente electromagnético en salas de rehabilitación / Evaluation of the electromagnetic environment in rehabilitation wards

Se realizó un estudio del ambiente electromagnético en 2 departamentos de electroterapia del municipio Palma Soriano de Santiago de Cuba, a fin de obtener el patrón de distribución para diferentes modos de operatividad y explotación del equipamiento médico-terapéutico. Para la caracterización electromagnética de los ambientes evaluados se elaboró un protocolo de medición a partir del análisis de normas internacionales y se empleó un medidor isotrópico que mostró los resultados a través de mapas de contorno. El equipo electromédico Magnetomed, modelo 7200 fue el que más aportó, aunque el valor máximo de la inducción magnética obtenido (19,7 µT) estuvo por debajo del límite de exposición establecido y por encima del límite de exposición sugerido por el Grupo de Trabajo Bioiniciativa. Se recomienda limitar la permanencia de personas en sus proximidades mientras está en funcionamiento.

A study of the electromagnetic environment was carried out in 2 electrotherapy departments of Palma Soriano in Santiago de Cuba, in order to obtain the distribution pattern for different operability ways and exploitation of the medical-therapeutic equipment. For the electromagnetic characterization of the evaluated environments a measurement protocol was elaborated starting from the analysis of international standards and an isotropic measure was used that showed the results through contour maps. The electro-medical device Magnetomed, model 7200 was the one that contributed the most, although the maximum value of the obtained magnetic induction (19.7 µT) was below the established exhibition limit and above the exhibition limit suggested by the Bioiniciativa Work Group. It is recommended to limit the permanency of people around, while it is in operation.

Evaluation of Electromagnetic Fields in a Hospital for Safe Use of Electronic Medical Equipment.

Establishment of electromagnetic compatibility is important in use of electronic medical equipment in hospitals. To evaluate the electromagnetic environment, the electric field intensity induced by electromagnetic radiation in broadcasting spectra coming from outside the hospital was measured in a new hospital building before any patients visited the hospital and 6 months after the opening of the hospital. Various incoming radio waves were detected on the upper floors, with no significant difference in measured levels before and after opening of the hospital. There were no cellphone terminal signals before the hospital opened, but these signals were strongly detected at 6 months thereafter. Cellphone base stations signals were strongly detected on the upper floors, but there were no signals at most locations in the basement and in the center of the building on the lower floors. A maximum electrical intensity of 0.28 V/m from cellphone base stations (2.1 GHz) was detected at the south end of the 2nd floor before the hospital opened. This value is lower than the EMC marginal value for general electronic medical equipment specified in IEC 60601-1-2 (3 V/m). Therefore, electromagnetic interference with electronic medical equipment is unlikely in this situation. However, cellphone terminal signals were frequently detected in non-base station signal areas. This is a concern, and understanding signal strength from cellphone base stations at a hospital is important for promotion of greater safety.

Analysis of operators knowledge of eletromagnet in complex electromagnetic environ-ments:a preliminary investigation / 军事医学

Objective To provide reference for protection evaluation of soldiers working in a complex electromagnetic environment by investigating their knowledge on electromagnetic radiation (EMR) protection via means of a questionnaire . Methods Ninety-eight soldiers working in complex electromagnetic environments were selected by random sampling .Ques-tionnaires were designed ,involving the hazard of and protection against EMR .Then the results of the survey were analyzed . Results Ninety-four questionnaires were collected .Results showed that the soldiers had some knowledge of the difference between EMR and ionizing radiation , and the hazard of and protection against EMR , but professional training was needed . In addition, their knowledge of the hazard of and protection against EMR could be improved through education .Conclusion The knowledge about EMR is insufficient among soldiers and needs to be improved .

Stochastic method for determination of the organ-specific averaged SAR in realistic environments at 950 MHz.

The organ-specific averaged specific absorption rate (SARosa ) in a heterogeneous human body phantom, the Virtual Family Boy, is determined for the first time in five realistic electromagnetic environments at the Global System for Mobile Communications downlink frequency of 950 MHz. We propose two methods based upon a fixed set of finite-difference time-domain (FDTD) simulations for generating cumulative distribution functions for the SARosa in a certain environment: an accurate vectorial cell-wise spline interpolation with an average error lower than 1.8%, and a faster scalar linear interpolation with a maximal average error of 14.3%. These errors are dependent on the angular steps chosen for the FDTD simulations. However, it is demonstrated that both methods provide the same shape of the cumulative distribution function for the studied organs in the considered environments. The SARosa depends on the considered organ and the environment. Two factors influencing the SARosa are investigated for the first time: conductivity over the density ratio of an organ, and the distance of the organ's center of gravity to the body's surface and exterior of the phantom. A non-linear regression with our model provides a correlation of 0.80. The SARosa due to single plane-wave exposure is also investigated; a worst-case single plane-wave exposure is determined for all studied organs and has been compared with realistic SARosa values. There is no fixed worst-case polarization for all organs, and a single plane-wave exposure condition that exceeds 91% of the SARosa values in a certain environment can always be found for the studied organs.

Discussion on the Defending Technologies for Military First-aid Equipments of the Army under Complex Electromagnetic Environments / 中国医学物理学杂志

Objective:To discuss the safety capability and defending technologies for military First-aid equipments of the army under complex electromagnetic environment.Methods:This paper analyzed the current status researching of the defending technologies for military First-aid medical equipments of the army,expatiated on the effect mechanism of the high power electromagnetic radiation on the medical equipment,and discussed the defending and reinforcing technologies.Results:The current military First-aid medical equipments of the army are of a sort defending capability,and it will have important significance to strengthen the study on the anti-electromagnetic interference technologies.Conclusion:The defending and reinforcing technologies discussed in this paper could enhance the subsistence capability of the military First-aid equipments under complex electromagnetic environments.

Discussion of Strengthening Subsistence Ability of Medical Equipment Under Complex Electromagnetic Environment / 医疗卫生装备

The survival ability of electro medical equipment under complex electromagnetic environment is researched and then various kinds of electromagnetic pulse threats of medical equipment are discussed.At last,the strategies on strengthening medical equipment electromagnetic protection capability are studied form the transfer ways of electromagnetic pollution.