In this paper the identification problem is considered for initial conditionsin a non-minimal state-space model that includes interpretable state variablesgenerated by non-stationary stochastic processes. In order to solve theidentification problem, structural restrictions are imposed on initial conditionsin a state-space model with redundant state variables. The correspondingrestricted maximum likelihood estimator of initial conditions is derived.The restricted estimator of initial conditions can be used in order tocompute uniquely identified realizations of interpretable latent variables. Theidentification problem is illustrated analytically using a simple structuraleconomic model.
The study deals with stability and dynamic problems in bar structures using a probabilistic approach. Structural design parameters are defined as deterministic values and also as random variables, which are not correlated. The criterion of structural failure is expressed by the condition of non-exceeding the admissible load multiplier and condition of non-exceeding the admissible vertical displacement. The Hasofer-Lind index was used as a reliability measure. The primary research tool is the FORM method. In order to verify the correctness of the calculations Monte Carlo and Importance Sampling methods were used. The sensitivity of the reliability index to the random variables was defined. The limit state function is not an explicit function of random variables. This dependence was determined using a numerical procedure, e.g. the finite element methods. The paper aims to present the communication between the STAND reliability analysis program and the KRATA and MES3D external FE programs.
This paper presents some new results on exogeneity in models with latent variables. The concept of exogeneity is extended to the class of models with latent variables, in which a subset of parameters and latent variables is of interest. Exogeneity is discussed from the Bayesian point of view. We propose sufficient weak and strong exogeneity conditions in the vector error correction model (VECM) with stochastic volatility (SV) disturbances. Finally, an empirical illustration based on the VECM-SV model for the daily growth rates of two main official Polish exchange rates: USD/PLN and EUR/PLN, as well as EUR/USD from the international Forex market is presented. The exogeneity of the EUR/USD rate is examined. The strong exogeneity hypothesis of the EUR/USD rate is not rejected by the data.
The paper presents the method of control of an induction squirrel-cage machine supplied by a voltage source converter. The presented idea is based on an innovative method of the voltage source converter control, consisting in direct joining of the motor control system with the voltage source rectifier control system. The combined control system gives good dc-bus voltage stabilization. In the applied control system the limits of the reference variables have been introduced. A correction of the estimated machine load torque is proposed. The new proposed solutions are confirmed by mathematical dependences, simulation and experimental results.
This paper presents a low-cost and smart measurement system to acquire and analyze mechanical motion parameters. The measurement system integrates several measuring nodes that include one or more triaxial accelerometers, a temperature sensor, a data acquisition unit and a wireless communication unit. Particular attention was dedicated to measurement system accuracy and compensation of measurement errors caused by power supply voltage variations, by temperature variations and by accelerometers’ misalignments. Mathematical relationships for error compensation were derived and software routines for measurement system configuration, data acquisition, data processing, and self-testing purposes were developed. The paper includes several simulation and experimental results obtained from an assembled prototype based on a crank-piston mechanism
The occurrence of gas confined in shales allows us to consider it as a component of the host rock. During drilling wells, the gas is released into the drilling fluid from finely ground gas-bearing rock particles. The amount of gas released can be determined on the basis of mud-gas logging; in addition, it is possible to determine the gas-content in shales expressed by the volume of gas released per mass unit of rock [m3/ton]. The gas content in the Ordovician and Silurian shales (Sasin formation and Jantar member respectively) in two selected wells in northern Poland was determined using this method. It has been found that clearly distinguishable, highly gas-bearing sections, which are separated by very poorly gas-bearing ones, can be determined in the well log. The increased gas content in shales can be observed in zones generally enriched in TOC. No direct correlation between TOC and gas-bearing capacity was found however, but the structure of TOC variability and the gas-bearing capacity described using variograms is identical. Correlations of the distinguished gas-bearing layers in the wells under consideration suggest a multi-lens or multi-layered reservoir model. The lack of natural boundaries in the shale gas reservoir means that they must be determined arbitrarily based on the assumed marginal gas-bearing capacity. In the case of several gas-bearing zones, numerous variants of interpretation are possible. In any case the low, best and high estimated resources may be evaluated, assigned to each borehole in the area with radii equal to the range of variogram of gas content in horizontal part of the well.
Stem canker and black scurf of potato (Solanum tuberosum L.) caused by Rhizoctonia solani Kühn are important and epidemic diseases in potato-growing regions worldwide, including Iran. In this study, 120 isolates were retrieved from infected stem canker from six potato- growing regions in Iran (Isfahan, Ardebil, Fars, Hamedan, Kurdestan and Kerman). Out of these, 30 isolates were selected as representatives for genetic and virulence analysis. The isolates were analyzed by one sequence analyzes of the ITS-rDNA region, random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR), as well as virulence studies. Based on sequence analysis of the ITS-rDNA region, all 30 isolates were assigned to the anastomosis group (AG) and all were assigned to AG-3 PT. Cluster analysis using the unweighted pair group method with the arithmetic averages (UPGMA) method for both RAPD and ISSR markers revealed that they were divided into three main groups, with no correlation to geographical regions of the isolates. Pathogenicity tests showed that all isolates were pathogenic on potato cv. Agria; however, virulence variability was observed among the isolates. The grouping based on RAPD analysis and virulence variability was not correlated.
From the regulatory point of view a strong link between an animal model and human pharmacodynamics of biological drugs is very important to qualify the model as “relevant”. Consistent changes in cell population between human physiology and animal model gain value of this model which then can be pharmacodynamically “relevant” from the regulatory point of view. Consequently, the aim of this study was to determine how similar to human observations is the effect of selected biological drugs on blood cells in a pig model. The study was to carry out a comparative analysis of the variability of selected biochemical and hematological parameters of the blood after administration of five different human therapeutic monoclonal antibodies (mAbs) after a single subcutaneous (SC) dose in breeding pigs. The tested drugs were siltuximab (Syl- vant®), omalizumab (Xolair®), infliximab (Inflectra®), pembrolizumab (Keytruda®), and vedoli- zumab (Entyvio®) given in a single 1 mg/kg SC injection. Each of the tested drugs exerted a sig- nificant effect on at least two of the tested parameters three weeks after the administration. Siltuximab significantly influenced 9 of the analyzed parameters. Vedolizumab significantly influenced 8 of the analyzed parameters. Infliximab had the lowest impact of all the tested drugs, as it significantly influenced only two of the analyzed parameters. The study has proved that the impact of mAbs on the analyzed parameters can be significantly extended over time. This requires the monitoring of hematological parameters in the pig model even many weeks af- ter administration of a drug in a relatively small dose.
The article presents the results of the second part of an eye-tracking study conducted on Polish secondary school students working with a textbook for learning English. 20 dyslexic and 20 non- dyslexic school students worked with two sets of materials that had different graphic layouts but the same content. Their eye movements were recorded. The analysed data show that the arrangement of the material and images on the textbook page influence both the way the students (especially dyslexic ones) work with the book and their results.
APNB (alkaline phenolic no bake), widely known as Alphaset is one of the major sand binder systems used in foundries to make molds and cores without application of heat or gas. This is a two part system comprising of a phenol-formaldehyde resin in alkaline medium as binder and range of esters of dibasic acids and/or polyhydric alcohols as hardeners.
Resin performance varies depending upon formulations. Major variables in formulations are mole ratio of phenol: formaldehyde, total alkali content, ratio of two alkalis (NaOH & KOH) and molecular weight of polymers i.e. chain length.
In present work, one mole ratio of phenol & formaldehyde has been chosen to prepare 8 resins with following details.
Table 1.
Physical and chemical properties of eight (fresh) resins, A to H
Properties | A | B | C | D | E | F | G | H |
Viscosity at 30°C (mPs-a) | 56 | 47 | 66 | 51 | 39 | 44 | 49 | 52 |
Na (%) | 5.94 | 3.21 | 5.94 | 3.21 | nil | 2.73 | nil | 2.73 |
K (%) | nil | 3.31 | nil | 3.31 | 7.18 | 3.87 | 7.18 | 3.87 |
Molecular weight | Low | Low | High | High | Low | Low | High | High |
Gel Time at 121°C, mt-sec | 27-0 | 29-30 | 24-0 | 30-0 | 30-0 | 27-30 | 26-30 | 26-0 |
Moisture (%) | 52.43 | 52.42 | 53.01 | 53.75 | 55.58 | 54.12 | 51.61 | 54.03 |
Non-volatile Content (%) | 48.74 | 47.25 | 49.10 | 49.35 | 47.63 | 47.32 | 48.06 | 48.29 |
Specific Gravity | 1.182 | 1.177 | 1.183 | 1.180 | 1.172 | 1.184 | 1.178 | 1.188 |
Free Phenol (%) | 0.47 | 0.42 | 0.44 | 0.43 | 0.37 | 0.27 | 0.41 | 0.20 |
Properties of these 8 formulations have been studied for strength and viscosity over a period of 12 weeks in 4 week interval.
Attempt has been made to develop a simple test for simulating hot & retained strength of molds in laboratory. Process followed for chasing hot and retained strength is described under clause 2.
With more and more understanding of the chemistry of alphaset system in last three & half decades it has been possible to identify role of variables contributing towards specific properties vis a vis developing tailor made formulations to fulfill requirements of individual foundries right from mold making to de coring.
The author defends the thesis that language is an attribute of a nation and as such it is offi cially protected by the international legal system irrespective of the number of its speakers; thus, there is no such phenomenon as a “little language”. Linguistic minorities speak their mother languages or some dialectal variants of those languages
The dynamic changes in selected heavy metal concentrations were analyzed in two ombrotrophic peat bogs from southern Poland: Puścizna Mala (PK) and Puścizna Krauszowska (PM). The highest contents of Pb and Zn occur at the top of profiles examined: 115.36 mg/kg (PM1), 90.61 mg/kg (PM2), 182.40 mg/kg (PK1), 121.68 mg/kg (PK2) and 127.43 mg/kg (PM1), 89.73 mg/kg (PM2), 170 mg/kg (PK1), 130.4 mg/kg (PK2), respectively. Concentrations of copper are similar to those of local soils varying from 9.4 to 12.8 mg/kg. Cadmium strongly varies with depth, which indicates distinct mobility of this element. Two peaks of elevated Fe concentrations are observed at the top and bottom of the Puścizna Mala profile, while the maximum in Puścizna Krauszowska was at the top of the peat bog. The Ti content distinctly varies with depth and correlates with the ash content (R 2 = 0.91-0.99). The strongest and positive correlation is observed between Zn-Pb and Ti-Pb contents. The significant differences of metal concentrations are noted between the profiles, which is probably connected with a rate of peat accumulation and plant composition of the profiles investigated, as well as with their disturbance by human activity.
Zooplankton was investigated at fixed site in 24 hours in Kongsfjorden, a glacial fjord situated on the west coast of Spitsbergen (Svalbard) (79°N, 12°E), in order to unveil the level of diurnal variability in community composition and abundance. Parallel to zooplankton study water temperature and salinity were measured while information on local tides and winds was obtained from external sources. Observed changes did not exceed the range of variability regarded intrinsic, resulting from the nature of plankton. Because of this low variability we are of the opinion that the data presented can be regarded a valid measure of the natural heterogeneity of zooplankton communities in hydrologically dynamic Arctic coastal waters in summer. The observed changes in zooplankton were primarily induced by the complex dynamics of the fjord’s water masses. In spite of importance of tidal forcing, the variability in zooplankton did not demonstrate similar temporal fluctuations due to modification of the water movement by other irregular forces (local wind). Also, we have not found any indication of diel vertical migration in coastal water in the Arctic under the condition of midnight sun.
News might trigger jump arrivals in financial time series. The “bad” news and “good” news seem to have distinct impact. In the research, a double exponential jump distribution is applied to model downward and upward jumps. Bayesian double exponential jump-diffusion model is proposed. Theorems stated in the paper enable estimation of the model’s parameters, detection of jumps and analysis of jump frequency. The methodology, founded upon the idea of latent variables, is illustrated with simulated data.