Hydrometeor and Latent Heat Nudging for Radar Reflectivity Assimilation: Response to the Model States and Uncertainties

Radar data are essential to convection nowcasting and nudging-based radar data assimilation through diabatic initialization is one of the most effective approaches for forecasting convective systems with numerical weather prediction (NWP) models, used at several advanced global weather centers. It is desired to assess the uncertainty and physical consistency of this assimilation process. This paper investigated impacts of relaxation coefficient, radar data update intervals and continuous assimilation time duration and addressed the key issues and possible solutions of the radar data assimilation based on the WRF hydrometeor and latent heat nudging (HLHN) developed at the National Center for Atmospheric Research (NCAR). It is revealed that excessively large relaxation coefficient forced the model to observations with a tendency greater than the physical terms of the convection, causing the dynamic imbalances and serious convection “ramp-down” right after the free forecast starts. Assimilating high update frequency radar data can make the tendency terms moderate and sustained thereby maintaining the assimilation effect and reducing fortuitous convection. HLHN requires a minimum continuous assimilation duration to contain the initial forced disturbance of the model. For a summer Meiyu precipitation case studied, the minimum duration is ~1 h. Appropriate selection of the HLHN parameters is able to effectively improve the temperature, humidity, and dynamic fields of the model. In addition, several issues still remain to be solved to further enhance HLHN.

Glucose detection of ringer-lactate solution using electrical bioimpedance: preliminary results

Continuous glucose monitoring is essential to reduce the damages caused by diabetes and for choosing the right treatment approach. In most cases, non-invasive glucose measurement devices generate their results through statistical tools (e.g., artificial neural networks) with an error that increases the further away from the training sample the measurement is. An analytical model would contain only propagated errors. Impedance measurements of lactate ringer’s solutions with egg albumin containing different concentrations of sugar were performed to validate the model proposed for measuring glycemia in human blood using the electrical bioimpedance meter AD5933. The curve fitting showed errors lower than 1.5%. Chemical phenomena, such as reduced sugar, fructosamine and solvation, might explain the behaviors observed in the experiments. The results suggest that the relaxation coefficient has significant changes with the increase of sugar in the solutions. The findings encourage future research with bovine blood for a more realistic analytical model.

High Speed PIV Measurements in Water Hammer

An experimental study addressing the challenge to measure relaxation coefficient of very fast phenomena such as water hammers is presented. An acrylic projectile containing water is accelerated and impacts a metal wall creating a water hammer. State of the art laser measurements techniques will be deployed in order to achieve such goal. A compressed air custom built cannon is used to accelerate the projectile and create the impact leading to the water hammer. First experimental results for Shadowgraphy and PIV measurements are presented and discussed with focus on the future development for the presented facility.

Influence of the Die Height on the Density of the Briquette Produced from Shredded Logging Residues

An alternative to plant biomass of various origins are forest logging residues. They differ significantly from other, previously used plant materials. This difference is due to the heterogeneous composition and relatively large size of individual particles. This research on the compaction of this type of shredded material was aimed at determining the influence of the die height on the density and relaxation of briquettes. This parameter is crucial for the proper construction of compaction devices. The measurements were carried out for the same fractional composition of the shredded logging residues, with variable input parameters of the material and process. It was found that the briquette density and relaxation are influenced by the die height, as well as the material moisture content and process temperature. The highest density at maximum compaction pressure (1.40 g·cm–3) was obtained at a moisture content of 16%, temperature of 80 °C, and the lowest die height (195 mm). In the case of the briquette density after ejection from the die, the best results were obtained at the same temperature and die height but at a moisture content of 9%. The tests confirmed that, regardless of the process temperature and material moisture, the briquette density increases as the die height is reduced. The relaxation coefficient of compacted logging residues ranges from 21.7% to 50.1% and depends mainly on the material moisture content and the temperature of the process. The lowest value of the relaxation coefficient (21.7 ± 1.61) was obtained at 9% moisture content, 60 °C temperature, and 220 mm die height.

General concept of determining the parameters of non-mining walls of ultra-deep diamond deposits development open pits

A specific feature of open pit mining of diamond deposits in Western Yakutia is the construction of the open pits in the zone of negative ambient temperatures, which includes thick permafrost rock mass, and which is at the same time complicated by the influence of cryogenic processes on deformation of pit wall benches. The paper presents the comparative analysis of strength characteristics in frozen and thawed rocks, stability of benches during mining, the general geomechanical approach to the determination of parameters of non-mining walls of the ultra-deep open pit diamond mines, and the parameters of nonmining walls and benches. Optimization of open pit wall configuration should primarily be based on the maximum utilization of the strength properties of frozen rocks in combination with the development of new approaches, calculation schemes and methods for assessing stability of open pit walls and benches of unconventional design, including the non-mining vertical benches. The main design characteristic that determines the parameters of open pit walls is the structural tectonic relaxation coefficient, which specifies the calculated value of cohesion in rock mass. For the diamond deposits, the values of the structural relaxation coefficient were obtained in a series of field tests and back calculations. Full-scale tests were carried out both during exploration operations in underground mines and in open pits. The accuracy of determining the values of the structural relaxation coefficient in the range of 0.085–0.11 is confirmed by the parameters of non-mining walls in an open pit mine 385–640 m deep, with overall slope angles of 38–55° and a steeper H 0.35–0.5 lower part having the slope angle of up to 70° with average strength characteristics of 7.85–11.84 MPa and the internal friction angle of 28.1–37.4°. Using the natural load-bearing capacity of rock mass to the full advantage, which the values of the structural relaxation coefficient of deposits show, allows optimization of open pit wall slope design and minimization of stripping operations.

Improved ISPH method for natural convection from heated T-open pipe of Al2O3-water nanofluid in a cavity: Buongiorno’s two-phase model

The unsteady natural convection of Al2O3-water nanofluid form heated open T-pipe inside a cavity has been investigated by ISPH method using non-homogenous two-phase Buongiorno's model. Different lengths and heights of T-pipe shape are considered. The side walls of the cavity are kept at cool temperature Tc and the horizontal walls are thermally insulated. The Lagrangian description of the controlling governing equations is discretized and solved using improved ISPH method. In this study, ISPH method is improved using kernel renormalization function for boundary treatment plus modification in the source term of pressure Poisson equation (PPE). The source term of PPE contains the velocity divergence plus density invariance multiply by relaxation coefficient. The calculations are performed for variable lengths of T-open pipe (0.2 ? Lb ? 0.6variable widths of T-open pipe (0.02 ?Wb?0.16), (0.02? Wt? 0.16) and variable concentration of nanoparticles volume fraction (1% ?.?avg ? 10). The obtained results showed that the maximum values of the stream function are reduced by 80.8% when ?avg is increased from 1% to 10%. Additionally, as lengths and widths of the T-pipe are raised, the average Nusselt numbers at the vertical walls are enhanced.

Phantom based quality assurance for long-term stability and inter-scanner compatibility in T1, T2 and T2* measurements

Funding Acknowledgements Type of funding sources: None. Background The quantitative measurement of T1, T2 and T2* relaxation parameters is prone to numerous physical variables related to scanner performance and installation environment. These variables include the presence of eddy currents, main magnetic field inhomogeneity and gradient field performance. Thus, it is important to verify that the measured relaxation parameters are inter-scanner compatible and there are no drift in the measured values over time. Purpose In this study, we produced a phantom for the relaxation parameter measurements. With the phantom, long-time stability and inter-scanner comparison of parameters were studied with preliminary quality assurance protocol. Methods A cylindrical quality assurance phantom with 16 inserts filled with ammonium iron(II) ((NH4)2Fe(SO4)2 · 6H2O) doped gel was produced. The (NH4)2Fe(SO4)2 concentrations were from 0,0119 mmol/g to 0,5498 mmol/g, corresponding to approximate T1 values of 10–1030 ms, T2 values of 16–78 ms and T2* values of 5–61 ms. The phantom was measured quarterly for a one-year period with three scanners from two different vendors to follow the scanner stability and inter-scanner compatibility. The used imaging sequences included T1 MOLLI -based sequence, T2 prep -based sequence, and multi-echo gradient echo sequence for T2* calculation. Simulated ECG signal with 60 beats per minute was used in the scanning to mimic a typical rest heart rate of an adult patient. Results The range of variation between scanners from average relaxation coefficient in T1 was -2% to 4% and in T2 and T2* measurements -7% to 5% and -32% to 18%, respectively. In long-term stability test, the range of variation from average relaxation coefficient in T1 was -1% to 2% and in T2 and T2* measurements -1% to 1% and -15% to 16%, respectively. Conclusion(s) There were significant differences in the measured T1, T2, and T2* relaxation coefficients in both inter-scanner and long-term stability. However, the detected variations were acceptable compared to the typical physiological uncertainties of the measured parameters but have to be taken into account when the reliability of the study is assessed. Abstract Figure. Results and phantom image

Algorithm for analyzing the movement pattern of the temporomandibular joint musculararticular system based on multichannel electromyogram processing

Musculoskeletal system disorders is one of the priority directions in dentistry. They can manifest as Kosten's syndrome, snapping jaw, painful dysfunction syndrome, increased tooth abrasion, splits, breaks, pain and spasms in muscles, etc. The study set the following objectives: to develop an algorithm for analyzing the movement pattern of the muscular-articular system by developing an algorithm for recording, analyzing, filtering and processing multichannel electromyograms of the maxillofacial muscles. Analysis of the proposed algorithm for processing multichannel electromyograms showed that 7.2 % of multichannel electromyograms could not be analyzed due to patients' violations of the movement algorithm; 8.7 % of electromyogram checkpoint values were corrected. The group without dysfunctions of the temporomandibular joint is characterized by the prevalence of the relaxation coefficient of the left temporal muscle over the coefficient of the right muscle. The dysfunctioned group has the opposite result. The value of the compression ratio of the temporal muscles exceeding 2.5 is typical for the group with dysfunctions of the temporomandibular joint. The studied groups differ as much as possible when analyzing the relaxation coefficients of the temporal muscles. When analyzing this coefficient, it was possible to truly determine the presence or absence of violations in 50 %, falsely – in 16 % of cases. The coefficient of relaxation of the masticatory muscles made it possible to obtain a true state of 24 %, a false one – in 8 %. We concluded that the compression ratio is less suitable for separating patients with and without dysfunction of the temporomandibular joint.

A nonlinear semi-continuum model for silicon micro/nanosheets and its application in bending and vibration

Background: This paper is concerned with a nonlinear semi-continuum model for an ultrathin structure. The basic equations of the theoretical model for silicon micro/nanosheets are derived, and the geometric nonlinearity is introduced in the model. Methods: From two different approaches including the new strain energy and the new external potential energy, we establish the nonlinear semi-continuum theoretical model of silicon micro/nanosheets, respectively. A new dimensionless nonlinear semi-continuum parameter is defined. Based on the theoretical model, the characteristics of bending deformation and free vibration are revealed. Results: The relationships between bending deflection and atomic layers in thickness direction as well as the relaxation coefficient between atomic layers are analyzed. The resonance frequencies of free vibration and their relationship with atomic layers are calculated. By introducing the specific property parameters of silicon micro/nanomaterials, several numerical calculations have been carried out. Conclusion: The theoretical results are compared with other studies in the literature, such as nonlinear finite element method (FEM), experimental and classical results, to validate the semi-continuum model established in the present research. This work can provide new ideas for the mechanical analyses of micro/nanomaterials and structures, and the results could be foundations for the design and application of silicon micro/nanosheets.