MOM Model Research Articles

Optimization of benzene exposure risk assessment: An integrated approach utilizing internal and external concentrations with a focus on biomarkers S-PMA & t, t-MA

In the majority of occupational settings within China, the concentrations of benzene are observed to fall markedly below the demarcated detection thresholds. Employing traditional risk assessment models, the presence of exceptionally low airborne benzene exposure concentrations may infuse heightened degrees of uncertainty. Consequently, the necessity arises to investigate risk assessment methodologies more apt for the prevalent exposure environment among employees. In the present study, a pharmacokinetic model premised on urinary benzene metabolites (S-PMA and t, t-MA) was employed to ascertain a more precise daily airborne benzene exposure concentration per individual. This value was integrated into the linear multistage model as the ‘internal exposure concentration’. In conjunction with the U.S National Environmental Protection Agency's (EPA) inhalation risk assessment model predicated on the external exposure concentration, the Singapore Ministry of Manpower's (MOM) model, and the linear multistage (LMS) model, the carcinogenic and non-carcinogenic effects of benzene were evaluated for 1781 benzene-exposed employees across 76 enterprises in Jiangsu Province. Findings suggest that in the linear multilevel model assessment, the cancer risk levels based on t, t-MA and S-PMA were higher in the printing and recording media reproduction industry, automobile manufacturing industry, general equipment manufacturing industry and the furniture manufacturing industry (median 2.842 × 10−4, 2.819 × 10−4, 2.809 × 10−4, and 2.678 × 10−4), which align more consistently with the actual benzene exposure circumstances of each industry's study participants, with overall risk levels calculated by the linear multistage model exceeding those of the EPA inhalation risk assessment model and the MOM model. This implies that the linear multistage model of internal exposure, based on the reciprocal of benzene biomarkers S-PMA and t, t-MA for airborne benzene exposure, presents enhanced sensitivity and suitability for the current occupational health risk assessment of workers. Without doubt, biomarker-based benzene exposure risk assessment emerges as the optimal choice.

Effect of frequency on activation energy and its role in producing piezoelectricity for Ruddlesden Popper oxide Ba2SnO4

In this work, we have clarified and studied in depth the complicated alternating current (AC) mechanisms for the Ruddlesden Popper (RP) Oxide Ba2SnO4, which is an ionic material presenting high compatibility with the modified OLPT model MOM. This study allows filtering the difference between a piezoelectric and not piezoelectric material having both the MOM model. In this work, we show the significant impact of the stability of the Tendency to the Activation Energy (TAE) with the frequency variation (in the active band) in the appearance and the persistence of the ionic transporter of its acoustic lattice vibration: phonion. This latter is fundamental in ensuring the MOM mechanism in both materials (piezoelectric or not). Moreover, we have highlighted the microscopic reverse piezoelectric behavior and the role played by both the value and the resistance of the tendency to the activation energy (TAE) to reveal an eventual piezoelectric phenomenon.

Occupational health risk assessment of the benzene exposure industries: a comprehensive scoring method through 4 health risk assessment models

Benzene is one of the most common occupational hazards in the working environment which was in the list of group 1 carcinogens. This study applied four occupational health risk assessment models: EPA model; MOM model of Singapore; the International Council on Mining and Metals (ICMM) model, and the Technical guide WS/T 777-2021 of China. The models assessed both non-carcinogenic and carcinogenic effects of benzene for 1629 employees in 50 factories in Jiangsu Province (China) who were exposed to benzene in the working environment and analysis the risk between industries by principal component analysis (PCA) method. The highest occupational health hazard of benzene among the five industries is petroleum processing industry, then followed by chemical products manufacturing industry, special equipment manufacturing industry, wood processing and products industry, and at last the pharmaceutical manufacturing industry. The population of abnormal routine blood parameters in the subjects was mostly in the "wood products industry" group, and the concentration of benzene in "wood products industry" group is the lowest in 5 groups. The industries with low exposure concentration have higher blood abnormality rates; this may be caused by the fact that blood damage is more secretive under low occupational health risk.

CYLINDRICAL MICROSTRIP ARRAY ANTENNAS WITH SLOTTED STRIP-FRAMED PATCHES

A cylindrical microstrip array antenna with 5 pairs of coupled slotted strip framed patches is analyzed. The patches are proximity-fed by a cylindrical microstrip line. In order to extract the re∞ection coe-cient from the standing wave pattern on the microstrip line, its length is about 5 wavelengths. To the best of the authors' knowledge proximity-fed cylindrical arrays have not been analyzed before using a rigorous MOM model that takes into account all electromagnetic couplings between patches and feeding line. The paper consists of three parts. The flrst part describes a plane wave excitation of the cylindrical microstrip structure. It introduces some innovating theoretical developments, like the improvement of the asymptote for the spectral Green's function and the explicit surface wave contribution. The second part calculates the radar cross section of the cylindrical microstrip structure with single and coupled slotted strip framed patches. The resonant frequencies, and the amplitude and phase of the current distribution are analysed. The third part describes a design for a proximity-fed array of 5 coupled slotted strip framed patches. It gives the re∞ection coe-cient, current distribution on the patches, and radiation pattern. A very low level of cross polarization (< i40dB) is achieved. It is shown that the resonant frequencies of the cylindrical array and its planar analogue lie very close to each other. This is due to the common nature of the low frequency slot resonance for the slotted strip framed patch.

Detection of Radiated EM Transients by Exploiting Compact Spherical Antenna Features

In this paper, the features of a compact spherical antenna, already efficiently used for ultra wide band applications, are investigated by exploiting the possibility of detecting electromagnetic transients with frequency content up to the very high frequency range. Transient phenomena with the above mentioned frequency content are those encountered, for example, in partial discharge detection. The behaviour of the adopted compact spherical antenna enables to successfully detect the waveform of typical partial discharge transient radiated electromagnetic field, so preserving the information necessary for the subsequent pattern analysis, typically carried out by using classical conducted measures results. The compact antenna is firstly modelled by using two different moments method approaches in frequency domain: surface and thin-wire models are adopted in order to investigate different case studies so obtaining useful information about the behaviour of the antenna both in frequency and in time domain. Some comparisons with measured transient electromagnetic field data obtained with a real spherical antenna probe enable to successfully validate the use of the compact spherical antenna in detecting electromagnetic transients with frequency content up to the very high frequency range. A recent patent has been obtained also by one of the author by using this type of sensor. Keywords: Method of moments, numerical modeling, partial discharges, radiated electromagnetic fields, spherical antenna, transients, UWB antennas, EM Transients, MoM model, admittance of the probe

Carrying capacity: general principles of model construction

Carrying capacity is defined as the maximum biomass of a farmed species that can be supported without violating the maximum acceptable impacts to the farmed stock and its environment. Maximum acceptable impacts on the farmed stock and the environment are expressed by standards for water quality in the farm and the surrounding environment. Environmental quality standards are established in a political process. The scientific part of the problem to estimate the carrying capacity is to develop reliable, objective methods or models for estimating the response of both the environment and the farmed stock to farming. Using such models together with field observations from a specified locality and the quality standards in force, the carrying capacity for the locality can be estimated. Models must properly deal with hydrodynamic and biogeochemical and ecological processes in the environment as well as with oxygen consumption and sources and sinks of organic matter and nutrients due to farm activity. In this paper, the basic principles of model construction are discussed and the Norwegian MOM model is used as an example. Current speed data and farm activity data are identified as two generally large sources of uncertainty in estimates of environmental impact and carrying capacity.

Assessment of the impact of TS assimilation from ARGO floats in the Mediterranean Sea

Abstract. In this paper, the impact of assimilating Temperature (T) and Salinity (S) profiles from Argo floats in the Mediterranean Sea is quantitatively investigated using the Observing System Simulation Experiments (OSSE) approach. The impact of varying the number of floats and their launch positions is considered, using numerical simulations with a MOM model and a reduced-order multivariate Optimal Interpolation scheme (SOFA) for assimilation. Realistic float coverage and launch positions used during the first MFSTEP phase are considered, as well as "ideal" density coverage that can be envisioned for the future, corresponding to a double coverage with respect to MFSTEP and with floats released along the VOS tracks. The most effective float trajectories are identified, showing that frontal regions play a major role, and that it is crucial to maintain a sufficient coverage of them. In addition to this, a comparison is also performed between the results obtained from MEDARGO floats in ideal conditions and results from "ideal" profiles taken at fixed points along the VOS tracks, as for the XBT data. For consistency the coverage considered is double the actual XBT coverage during MFSTEP, resulting in a threefold increase in the number of profiles compared to the MEDARGO experiment. The maximum error reduction is of approximately 10%, suggesting that spatially coarser profiles from floats can be more efficient since they follow flow features.

Characteristics of microstrip leaky wave antenna using the method of moments

An efficient MoM algorithm is introduced to analyse large travelling-wave structures, exemplified with a microstrip leaky wave antenna. The method utilises a combination of travelling-wave and subdomain basis functions for the current expansion to minimise the number of unknowns in the analysis. The propagation constants which characterise the modal expansions are evaluated efficiently by the algorithm for the implementation of the travelling-wave basis functions. As a result the model overcomes computer memory problems encountered by the conventional MoM model in analysing large antennas where a large impedance matrix is needed. The algorithm is capable of generating results as accurate as that of the conventional method while achieving substantial reduction in computation time and resources.

Irrigation Management in GAP

The multisectoral Southeastern Anatolia Project (GAP) is the largest regional developmentplan for one of the less developed parts of Turkey. The GAP project includes the irrigation of 1.7 million ha of land and generation of 27 billion kWh of hydroelectric power with an installed capacity of 7500 MW. In order to optimize the benefits to be obtained from irrigation and to ensure sustainable irrigation in the GAP area, the Government of Turkey has commissioned the GAP Management, and Operation Maintenance study (GAP MOM). The overall MOM model provides an institutional and organizational framework that promotes the most effective development of irrigated agriculture in the GAP region. This goal can be expressed as three major objectives: maximize net benefits, ensure sustainability and be implementable and flexible.