Control Run Research Articles

Co-Solvent Assisted Hydrothermal Liquefaction of Algal Biomass and Biocrude Upgrading

This study reports the hydrothermal liquefaction (HTL) of microalgae Spirulina platenesis in the presence of alcohol or formic acid co-solvents. HTL runs are performed in a 1.8-L batch reactor at 300 °C using an alcohol (methanol and ethanol) or formic acid co-solvent. Consequently, hydrodeoxygenation (HDO) of resultant algal biocrude is performed at 350 °C for 2 h under high hydrogen pressure (~725 psi) using the Ru/C catalyst. The HTL results are compared with the control HTL run performed in water only. The results of the study show that the addition of co-solvents leads to a 30–63% increased biocrude yield over the control HTL run. Formic acid results in a 59.0% yield of biocrude, the highest amongst all co-solvents tested. Resultant biocrudes from formic acid-assisted and ethanol-assisted HTL runs have 21.6% and 3.8–11.0% higher energy content, respectively, than that of the control run. However, that of the methanol-assisted HTL results in biocrude with 4.2–9.0% lower energy density. Viscosity of biocrude from methanol- or ethanol-assisted HTL is higher than the control HTL but formic acid-assisted HTL results in a less viscous biocrude product. In addition, the HDO study leads to a 40.6% yield of upgraded oil, which is characterized by a higher net energy content and lower O/C and N/C ratios when compared to the initial HTL biocrude.

Determining the appropriate mixing ratio in a multi-substrate anaerobic digestion of organic solid wastes employing Taguchi method.

The current research proposed a method for optimally combining feed input ratios in order to improve the quantity and quality of daily biogas production through optimizing the variable response level in the Taguchi method. The anaerobic digestion (AD) process of an existing plant in Iran was simulated through a set of two-stage pilot reactors under mesophilic temperature conditions in order to achieve optimal operational performance. Three common substrates (organic fraction of municipal solid wastes, fruit and vegetable wastes, and horse manure) along with two recirculated materials; the post-digestion sludge and the secondary digester slurry, were investigated in 16 experimental runs based on four different pre-surface hypotheses. Comparison of the results of daily biogas energy (J/d/g-VS) in Run#9, to which the actual yield of hydrogen sulfide was minimal in parallel to a methane yield above 100 mL/g-VS, with the result of the optimal run with the ratios provided by the model, showed that the daily biogas energy was improved by 50% comparing to the control Run that had similar conditions to which was being applied in the full-scale existing AD plant.

A process-oriented evaluation of CAMS reanalysis ozone during tropopause folds over Europe for the period 2003–2018

Abstract. Tropopause folds are the key process underlying stratosphere-to-troposphere transport (STT) of ozone, and thus they affect tropospheric ozone levels and variability. In the present study we perform a process-oriented evaluation of Copernicus Atmosphere Monitoring Service (CAMS) reanalysis (CAMSRA) O3 during folding events over Europe and for the time period from 2003 to 2018. A 3-D labeling algorithm is applied to detect tropopause folds in CAMSRA, while ozonesonde data from WOUDC (World Ozone and Ultraviolet Radiation Data Centre) and aircraft measurements from IAGOS (In-service Aircraft for a Global Observing System) are used for CAMSRA O3 evaluation. The profiles of observed and CAMSRA O3 concentrations indicate that CAMSRA reproduces the observed O3 increases in the troposphere during the examined folding events. Nevertheless, at most of the examined sites, CAMSRA overestimates the observed O3 concentrations, mostly at the upper portion of the observed increases, with a median fractional gross error (FGE) among the examined sites >0.2 above 400 hPa. The use of a control run without data assimilation reveals that the aforementioned overestimation of CAMSRA O3 arises from the data assimilation implementation. Overall, although data assimilation assists CAMSRA O3 to follow the observed O3 enhancements in the troposphere during the STT events, it introduces biases in the upper troposphere resulting in no clear quantitative improvement compared to the control run without data assimilation. Less biased assimilated O3 products, with finer vertical resolution in the troposphere, in addition to higher IFS (Integrated Forecasting System) vertical resolution, are expected to provide a better representation of O3 variability during tropopause folds.

An Experimental Study of Endogenous Discretionary Controls on Employee Effort

Discretionary controls are controls that can be applied at the ex post discretion of the superior rather than being supported by pre-committed enforceable contracts. This study examines employees’ effort levels when a discretionary control is endogenously present (chosen by the superior) relative to when it is exogenously present (assigned by the experimenters). Results from our gift-exchange experiment regarding superiors’ choice of a discretionary control run counter to prior research on superiors’ choice to use pre-committed controls in two important ways. First, we find employee effort is unaffected by the superior’s choice of a discretionary control relative to when it is exogenous. That is, the intentional choice of a discretionary control does not seem to be resented by the employee. Second, we find employee effort is lower when superiors choose not to have a discretionary control present relative to when it is exogenously unavailable. That is, we not only find no reward to forgoing a discretionary control, but rather a cost to not choosing a discretionary control. In sum, our results support the prevalence of discretionary controls in practice.

Effects of Cloud Microphysics on the Universal Performance of Neural Network Radiation Scheme

AbstractUnderstanding the effect of cloud microphysical changes on the stability of radiation emulator is essential in an operational weather forecasting model with frequent updates. This study examined the effect of 15 microphysics schemes on a radiation emulator for real and ideal cases. In the real case, although the forecast errors against the control run increased with varying microphysics schemes to the trained scheme, the forecast error of 2‐m temperature was rather improved by 0.9%–5.4% when compared with observations. The radiation emulator for the real case was applied to an ideal squall‐line simulation to test its universal application, resulting in increase of 8.6%–41.3% more forecast errors in heating rates and fluxes for 14 microphysics schemes more than the trained scheme. These errors could be reduced by 26.5%–50.4% with the use of a compound parameterization. Therefore, the stability and accuracy of radiation emulator on microphysics changes was confirmed.

Implementation of an ensemble Kalman filter in the Community Multiscale Air Quality model (CMAQ model v5.1) for data assimilation of ground-level PM<sub>2.5</sub>

Abstract. In this study, we developed a data assimilation (DA) system for chemical transport model (CTM) simulations using an ensemble Kalman filter (EnKF) technique. This DA technique is easy to implement in an existing system without seriously modifying the original CTM and can provide flow-dependent corrections based on error covariance by short-term ensemble propagations. First, the PM2.5 observations at ground stations were assimilated in this DA system every 6 h over South Korea for the period of the KORUS–AQ campaign from 1 May to 12 June 2016. The DA performances with the EnKF were then compared to a control run (CTR) without DA and a run with three-dimensional variational (3D-Var) DA. Consistent improvements owing to the initial conditions (ICs) assimilated with the EnKF were found in the DA experiments at a 6 h interval compared to the CTR run and to the run with 3D-Var. In addition, we attempted to assimilate the ground observations from China to examine the impacts of improved boundary conditions (BCs) on the PM2.5 predictability over South Korea. The contributions of the ICs and BCs to improvements in the PM2.5 predictability were also quantified. For example, the relative reductions in terms of the normalized mean bias (NMB) were found to be approximately 27.2 % for the 6 h reanalysis run. A series of 24 h PM2.5 predictions were additionally conducted each day at 00:00 UTC with the optimized ICs. The relative reduction of the NMB was 17.3 % for the 24 h prediction run when the updated ICs were applied at 00:00 UTC. This means that after the application of the updated BCs, an additional 9.0 % reduction in the NMB was achieved for 24 h PM2.5 predictions in South Korea.

Impact of Treadmill Interval Running on the Appearance of Zinc Finger Protein FHL2 in Bone Marrow Cells in a Rat Model: A Pilot Study.

Although the benefits of physical exercise to preserve bone quality are now widely recognized, the intimate mechanisms leading to the underlying cell responses still require further investigations. Interval training running, for instance, appears as a generator of impacts on the skeleton, and particularly on the progenitor cells located in the bone marrow. Therefore, if this kind of stimulus initiates bone cell proliferation and differentiation, the activation of a devoted signaling pathway by mechano-transduction seems likely. This study aimed at investigating the effects of an interval running program on the appearance of the zinc finger protein FHL2 in bone cells and their anatomical location. Twelve 5-week-old male Wistar rats were randomly allocated to one of the following groups (n = 6 per group): sedentary control (SED) or high-intensity interval running (EX, 8 consecutive weeks). FHL2 identification in bone cells was performed by immuno-histochemistry on serial sections of radii. We hypothesized that impacts generated by running could activate, in vivo, a specific signaling pathway, through an integrin-mediated mechano-transductive process, leading to the synthesis of FHL2 in bone marrow cells. Our data demonstrated the systematic appearance of FHL2 (% labeled cells: 7.5%, p < 0.001) in bone marrow obtained from EX rats, whereas no FHL2 was revealed in SED rats. These results suggest that the mechanical impacts generated during high-intensity interval running activate a signaling pathway involving nuclear FHL2, such as that also observed with dexamethasone administration. Consequently, interval running could be proposed as a non-pharmacological strategy to contribute to bone marrow cell osteogenic differentiation.

Dynamic and Thermal Effects of the Tibetan and Iranian Plateaus on the Northward-Propagating Intraseasonal Oscillation during Boreal Summer

Abstract This study investigates the dynamic and thermal effects of the Tibetan and Iranian Plateaus (TIP) on the characteristics of the northward-propagating boreal summer intraseasonal oscillation (BSISO) and reveals associated physical mechanisms. The relative importance of the Tibetan Plateau (TP) and Iranian Plateau (IP) to the northward propagation of BSISO is also detected. The findings are based on comparative analyses of the control run and six sensitivity experiments using the atmospheric model component of CAS FGOALS-f3-L (the low-resolution version of the Chinese Academy of Sciences Flexible Global Ocean–Atmosphere–Land System model, finite-volume version 3). It is demonstrated that the absence of TIP surface sensible heat or terrain restricts the occurrence of upper-level easterly and lower-level westerly anomalies, as well as moisture convergence over the Asian summer monsoon (ASM) region, which leads to a weakened easterly vertical wind shear with a narrowed range and the generation of a negative meridional specific humidity gradient in the northern Bay of Bengal. These mean-state changes are not conducive to the formation of positive barotropic vorticity together with planetary boundary layer moisture convergence to the north of the convective center, thus impeding the northward propagation of the BSISO. Results indicate that the combined TIP area, via its dynamic and thermal effects, modulates the northward-propagating BSISO by directly affecting the vertical wind shear and meridional moisture gradient in the northern Indian Ocean. By contrast, the TP plays a decisive role in the BSISO northward propagation due to the limited dynamic and thermal effects of IP on the background circulation and water vapor convergence over the ASM region.

A new global ocean ensemble system at the Met Office: Assessing the impact of hybrid data assimilation and inflation settings

AbstractWe have developed a global ocean and sea‐ice ensemble forecasting system based on the operational forecasting ocean assimilation model (FOAM) system run at the Met Office. The ocean model Nucleus for European Modelling of the Ocean (NEMO) and the community ice code (CICE) sea‐ice model are run at 1/4 resolution and the system assimilates data using a three‐dimensional variational assimilation (3DVar) version of NEMOVAR. This data assimilation (DA) system can perform hybrid ensemble/variational assimilation. A 36‐member ensemble of hybrid ensemble variational assimilation systems with perturbed observations (values and locations) has been set up, with each member forced at the surface by a separate member of the Met Office Global–Regional Ensemble Prediction System (MOGREPS‐G). The unperturbed member is forced by atmospheric fields from the Met Office operational numerical weather prediction (NWP) deterministic system. The system includes stochastic model perturbations and a relaxation to prior spread (RTPS) inflation scheme. A control run of the system using an ensemble of 3DVars is shown to be generally reliable for Sea‐Level Anomaly (SLA), temperature, and salinity (the ensemble spread being a good representation of the uncertainty in the ensemble mean), although the ensemble is underspread in eddying regions. The ensemble mean gives a 4% reduction in error in SLA compared with the deterministic 3DVar system currently used operationally. The system was tested with different weights for the ensemble component of the hybrid background‐error covariance matrix and different inflation factors. The best results, in terms of short‐range forecast error and ensemble reliability statistics, were obtained with hybrid three‐dimensional ensemble variational DA (3DEnVar). The RTPS inflation scheme is shown to be beneficial in producing an appropriate ensemble spread in response to hybrid DA. 3DEnVar with an ensemble hybrid weight of 0.8 leads to a reduction of 20% (5%) in the ensemble mean error for SLA (profile temperature and salinity) compared with an ensemble of standard 3DVars.

Identifying the changes in winter monsoon characteristics over the Indian subcontinent due to Arabian Sea warming

This study investigated the impact of the Arabian Sea (AS) warming in modulating the winter precipitation over the Indian subcontinent and associated dynamical response such as subtropical jet variability using regional climate model, RegCM4.7 of the International Centre for Theoretical Physics (ICTP). In this regard, a control run (RegCTL) is forced by real sea surface temperature (SST), and two sensitivity experiments with uniformly increased SST over AS by 0.45 °C (RegSST45) and 0.90 °C (RegSST90) are performed. The results obtained from a control experiment (RegCTL) are compared with corresponding values from RegSST45 and RegSST90 to assess the warming impact. The model (RegCTL) realistically simulates the circulation features, precipitation, and temperature over the Indian subcontinents in the winter season (November–December-January-February; NDJF) during 2006–2015. It is found that AS warming increases the precipitation over most parts of India during winter. The precipitation response varies with the month (NDJF) and the magnitude of AS warming. In general, precipitation is found to intensify with increasing AS warming over northern India and adjoining south Asian nations like Afghanistan, Pakistan, and some parts of Burma and Nepal. The strengthening of STJ is observed due to AS warming (RegSST45). The strengthening of the subtropical jet (STJ) persists with an intensification of AS warming (RegSST90); however, the magnitude of strengthening is less than RegSST45, which is consistent with the corresponding increase of precipitation over India. Cold wave duration is found to be significantly sensitive to the intensity of AS warming. It is noticed that the AS warming increases the cold wave duration over the northern part of India with major increases over the western Himalayan region.

Orographic enhancement of rainfall over the Congo Basin

AbstractThe Congo rainforest located in central equatorial Africa is an important, yet understudied part of the globe surrounded by complex orographic features. A primitive understanding of precipitation processes such as mesoscale convective dynamics magnifies uncertainties in the future climate projections of the hydrological cycle over the Congo. Furthermore, the effects of orography, which is an important forcing for convection and precipitation, are poorly resolved by climate models, and ill‐conceptualized over the Congo. To address this knowledge gap, perturbed orographic forcing experiments are conducted using the Weather Research and Forecasting (WRF) mesoscale numerical model in a high‐resolution convection‐permitting model setup. The model simulated selected dates in November 2014. The thunderstorms and rainfall simulated in the control run for the case study analyzed in this article compared reasonably well to satellite‐derived brightness temperature and rainfall data. The results from this case study show that the dynamical impact of increasing the height of the East African Highlands is the blocking of the lower‐tropospheric tropical easterlies. This weakening of the lower‐tropospheric zonal winds increases the windshear over the Congo Basin resulting in slower propagating, more intense mesoscale convective systems with enhanced rainfall.

An FSO-based Optimization Framework for Improved Observation Performance: Theoretical Formulation and Experiments with NAVDAS-AR/NAVGEM

Abstract The forecast sensitivity to observations (FSO) is embedded into a new optimization framework for improving the observation performance in atmospheric data assimilation. Key ingredients are introduced as follows: the innovation-weight parametrization of the analysis equation, the FSO-based evaluation of the forecast error gradient to parameters, a line search approach to optimization, and an efficient mechanism for step length specification. This methodology is tested in preliminary numerical experiments with the Naval Research Laboratory Atmospheric Variational Data Assimilation System-Accelerated Representer (NAVDAS-AR) and the U.S. Navy’s Global Environmental Model (NAVGEM) at a T425L60 resolution. The experimental setup relies on a verification state produced by the European Centre for Medium-Range Weather Forecasts (ECMWF) to estimate the analysis and short-range forecast errors. Parameter tuning is implemented in a training stage valid for April 1-14 of 2018 and aimed at improving the use of assimilated observations in reducing the initial-condition errors. Assessment is carried out for April 15 – May 31 of 2018 to investigate the performance of the weighted assimilation system in reducing the errors in analyses and 24-hour model forecasts. In average, as compared with the control run and verified against the ECMWF analyses, the weighted approach provided 17.4% reduction in analysis errors and 3.1% reduction in 24-hour forecast errors, measured in a dry total energy norm. Observation impacts are calculated to assess the use of various observation types in reducing the analysis and forecast errors. In particular, assimilation of satellite wind data is significantly improved through the innovation-weighting procedure.

Radiative Cooling, Latent Heating, and Cloud Ice in the Tropical Upper Troposphere

Abstract The radiative cooling rate in the tropical upper troposphere is expected to increase as climate warms. Since the tropics are approximately in radiative–convective equilibrium (RCE), this implies an increase in the convective heating rate, which is the sum of the latent heating rate and the eddy heat flux convergence. We examine the impact of these changes on the vertical profile of cloud ice amount in cloud-resolving simulations of RCE. Three simulations are conducted: a control run, a warming run, and an experimental run in which there is no warming but a temperature forcing is imposed to mimic the warming-induced increase in radiative cooling. Surface warming causes a reduction in cloud fraction at all upper-tropospheric temperature levels but an increase in the ice mixing ratio within deep convective cores. The experimental run has more cloud ice than the warming run at fixed temperature despite the fact that their latent heating rates are equal, which suggests that the efficiency of latent heating by cloud ice increases with warming. An analytic expression relating the ice-related latent heating rate to a number of other factors is derived and used to understand the model results. This reveals that the increase in latent heating efficiency is driven mostly by 1) the migration of isotherms to lower pressure and 2) a slight warming of the top of the convective layer. These physically robust changes act to reduce the residence time of ice at any particular temperature level, which tempers the response of the mean cloud ice profile to warming. Significance Statement Here we examine how the amount of condensed ice in part of the atmosphere—the tropical upper troposphere (UT)—responds to global warming. In the UT, the energy released during ice formation is balanced by the emission of radiation to space. This emission will strengthen with warming, suggesting that there will also be more ice. Using a model of the tropical atmosphere, we find that the increase in ice amount is mitigated by a reduction in the amount of time ice spends in the UT. This could have important implications for the cloud response to global warming, and future work should focus on how these changes are manifested across the distribution of convective cloud types.

The Impact of a Reduced High‐Wind Charnock Parameter on Wave Growth With Application to the North Sea, the Norwegian Sea, and the Arctic Ocean

AbstractAs atmospheric models move to higher resolution and resolve smaller scales, the maximum modeled wind speed also tends to increase. Wave models tuned to coarser wind fields tend to overestimate the wave growth under strong winds. A recently developed semiempirical parameterization of the Charnock parameter, which controls the roughness length over surface waves, substantially reduces the aerodynamic drag of waves in high winds (above a threshold of 30 m s−1). Here, we apply the formulation in a recent version of the wave model WAM (Cycle 4.7), which uses a modified version of the physics parameterizations by Ardhuin et al. (2010, https://doi.org/10.1175/2010jpo4324.1) as well as subgrid obstructions for better performance around complex topography. The new Charnock formulation is tested with wind forcing from NORA3, a recently completed nonhydrostatic atmospheric downscaling of the global reanalysis ERA5 for the North Sea, the Norwegian Sea and the Barents Sea. Such high‐resolution atmospheric model integrations tend to have stronger (and more realistic) upper‐percentile winds than what is typically found in coarser atmospheric models. A 2‐year comparison (2011–2012) of a control run against the run with the modified Charnock parameter shows a dramatic reduction of the wave height bias in high‐wind cases. The added computational cost of the new physics and the reduction of the Charnock parameter compared to the earlier WAM physics is modest (14%). A longer (1998–2020) hindcast integration with the new Charnock parameter is found to compare well against in situ and altimeter wave measurements both for intermediate and high sea states.

The Impacts of Hydrometeors and Water Vapor in Stratiform Region on the Evolutions of MCSs and Embedded Convective Cells in a Pre‐Summer Rainfall Event Over South China

AbstractBoth the stratiform and convective regions play important roles in the development of mesoscale convective systems (MCSs). In this study, the impacts of hydrometeors and water vapor in stratiform region on the evolution of MCSs during a heavy rainfall event over South China are investigated by the Weather Research and Forecasting (WRF) model with Thompson microphysics. A series of sensitivity experiments including the reductions of water vapor to 95%, 80% (water vapor sensitivity experiments), and the reductions of hydrometeor mixing ratios to 10% (hydrometeor sensitivity experiments) in stratiform region are conducted, respectively. Results show that the control run reasonably reproduces the spatial distribution and temporal evolution of convective rainbands. The hydrometeor flux convergence partly indicates the changes of convection organization and movement direction. The intensities of precipitation and MCSs are significantly weakened by decreasing moisture advection to convective region in water vapor sensitivity experiments, but are a little weaker in hydrometeor sensitivity experiments. The enhanced water vapor advection and reduced sedimentation and evaporation of rain water in hydrometeor sensitivity experiments are responsible for the restoration of stratiform cloud. The stratiform region with more hydrometeors is generally more conducive to the development of convection than less one when they are at the same evolution stage. However, it is found that stronger convective cell can also exist in the stratiform region with less hydrometeors that is generated by the old convection cloud and at its dissipating stage, owing to the more transfer of water vapor and hydrometeors from stratiform to convective regions.

The Effect of Anthropogenic Heat and Moisture on Local Weather at Industrial Heat Islands: A Numerical Experiment

The current study addresses the role of heat and moisture emitted from anthropogenic sources on the local weather with the aid of numerical weather prediction (NWP). The heat and moisture emitted by industries to the atmosphere are considered main sources in this study. In order to understand the effect of heat and moisture on local weather, the study is conducted to capture the impact of heat with no moisture change. The results are compared against a control run case without perturbation and also against the case where both heat and moisture are perturbed with temperature as a single parameter. The Angul district in Odisha that houses over 4000 industries is considered our study region. The numerical simulations are performed using the mesoscale Weather Research and Forecasting (WRF) model for two rain events, namely a light rain case and a heavy rain case, with different physics options available in the WRF model. The WRF simulated maximum rainfall rate using various microphysics schemes are compared with the Tropical rainfall measuring mission (TRMM) observations for validation purposes. Our study shows that the WDM6 double moment microphysics scheme is better in capturing rain events. The TRMM-validated WRF simulation is considered a reference state of the atmosphere against which comparisons for the perturbed case are made. The surface temperature is perturbed by increasing it by 10 K near the industrial site and exponentially decreasing it with height up to the atmospheric boundary layer. A numerical experiment represents heating without addition of moisture by recalculating the relative humidity (RH) corresponding to the perturbed temperature. The perturbed temperature affects sensible heat (SH) and latent heat (LH) parameters in the numerical experiment. From the results of the numerical investigation, it is found that the near-surface rainfall rate increases locally in a reasonable manner with the addition of sensible heat to the atmosphere. A comparison against the case where moisture is added shows that enhanced rainfall is more sensitive to sensible and latent heat than sensible heat alone.

Grafting Hollow Covalent Organic Framework Nanoparticles with Thermal-Responsive Polymers for the Controlled Release of Preservatives.

Covalent organic frameworks (COFs) hold great potential in various applications because of their well-defined pore structures and morphologies. However, most COF materials demonstrate poor dispersibility in solvents that significantly limits their processing and applications. Herein, we report the synthesis of COF-based hollow nanoparticles (h-NPs) with good water dispersibility, high capacity, and thermal responsiveness to load essential oil molecules for longer-term preservation of fruits. Imine-based COF h-NPs possessing a pore width of 1.3 nm, inner/outer diameters of ∼150/239 nm, and high crystallinity were synthesized and grafted with water-soluble polymers such as polyethylene glycol or poly(N-isopropylacrylamide) (PNIPAM) with molecular weights of 1-3 kDa. The h-NP products with grafting densities of 0.6-2.1 nm-2 can be well dispersed in water at room temperature. PNIPAM-grafted ones are temperature-responsive in that they can precipitate out from the dispersion at 40 °C and redisperse at 25 °C for at least 15 cycles. The h-NPs are used as nanocarriers to load essential oils such as hexanal and trans-2-hexenal with a high capacity of 1.1 g/g for fruit fresh-keeping, and the encapsulated preservatives can be released controllably at 25-40 °C as regulated by the grafted polymers. As a result, the storage time of cherry tomatoes can be prolonged by 4 days compared to the control run. Moreover, these h-NPs can be recycled and reused. Our work highlights the potential of COF nanomaterials grafting with stimuli-responsive polymers for controlled release application in various food preservation.

Distributed Cruise Control and Comfort Evaluation for High-speed Trains Under Moving Block Mode

This paper investigates the problems of distributed cooperative cruise control and train running comfort for high-speed trains with input constraints under moving block mode. Firstly, inspired by the mode of hitting a hard wall for moving block, a distributed cooperative cruise control algorithm based on the position and speed state information of adjacent trains is proposed. Under this control algorithm, all trains can track the given speed and realize speed cruise. In this algorithm, the relationship between speed and displacement is used to improve the position term, so as to achieve the minimum safe distance between trains by adjusting the speed. Secondly, aiming at the problem of the excessive acceleration of each train in the moving block mode, the hyperbolic tangent function is introduced to limit the acceleration of each train in an appropriate range by limiting the control input. Finally, the stability of the closed-loop system in error state is proved by using Lyapunov stability theorem, and the feasibility of the algorithm is verified by simulation.

Low‐Level Jets and the Convergence of Mars Data Assimilation Algorithms

AbstractData assimilation is an increasingly popular technique in Mars atmospheric science, but its effect on the mean states of the underlying atmosphere models has not been thoroughly examined. The robustness of results to the choice of model and assimilation algorithm also warrants further study. We investigate these issues using two Mars general circulation models (MGCMs), with particular emphasis on zonal wind and temperature fields. When temperature retrievals from the Mars Global Surveyor Thermal Emission Spectrometer (TES) are assimilated into the U.K.‐Laboratoire de Météorologie Dynamique MGCM to create the Mars Analysis Correction Data Assimilation (MACDA) reanalysis, low‐level zonal jets in the winter northern hemisphere shift equatorward and weaken relative to a free‐running control simulation from the same MGCM. The Ensemble Mars Atmosphere Reanalysis System (EMARS) reanalysis, which is also based on TES temperature retrievals, also shows jet weakening (but less if any shifting) relative to a control simulation performed with the underlying Geophysical Fluid Dynamics Laboratory MGCM. Examining higher levels of the atmosphere, monthly mean three‐dimensional temperature and zonal wind fields are in generally better agreement between the two reanalyses than between the two control simulations. In conjunction with information about the MGCMs' physical parameterizations, intercomparisons between the various reanalyses and control simulations suggest that overall the EMARS control run is plausibly less biased (relative to the true state of the Martian atmosphere) than the MACDA control run. Implications for future observational studies are discussed.

Optimization of the Conditions for Cultivation of Yersinia pseudotuberculosis in the Process of Obtaining Cell Mass

Objective of the study was to optimize the conditions of submerged recurrent cultivation and the composition of the nutrient medium for obtaining the cell mass of Yersinia pseudotuberculosis strains, used as an adsorbent in the preparation of diagnostic plague immunoglobulins. Materials and methods. We utilized Y. pseudotuberculosis adsorbent strains 6; 31; 68; 69; and 70 belonging to V, I, III, IV, and V serotypes, respectively, received from the State Collection of Pathogenic Bacteria at the premises of the RusRAPI “Microbe”. The cultivation process was carried out on an incubator-shaker, laboratory and pilot fermenters with variation of the process parameters, different options for feeding and nutrient media. Results and discussion. In the course of work, the optimal parameters of recurring submerged cultivation have been established. It was found that the highest biomass yield is provided by a combination of a nutrient medium – a carbon substrate in the form of a broth, based on an enzymatic fibrin hydrolysate, with the addition of galactose as a substrate feeding. Thereat, the morphology and immunochemical properties of microbial cells obtained through modified preparation process do not differ from those produced in the control run. The optimization of the parameters for Y. pseudotuberculosis cell mass cultivation with subsequent upscaling has been performed.