Comparative Analysis of Pitching Prediction Algorithms

Two algorithms are described in the paper; one of them is the Kalman filter, which is based on the use of a pitching mathematical model, and the second uses a neural network in which the model is considered unknown. The results of the algorithms sensitivity analysis to the parameters of the model and its influence on the potential accuracy of prediction are presented. A stationary narrow-band second-order Markov process is used as a model of the ship pitching, which was used to form the input signal of the algorithms. Also, the results of the algorithms simulation in predicting real data are presented.

Improving the potential accuracy and usability of EURO-CORDEX estimates of future rainfall climate using frequentist model averaging

Probabilities of future climate states can be estimated by fitting distributions to the members of an ensemble of climate model projections. The change in the ensemble mean can be used as an estimate of the change in the mean of the real climate. However, the level of sampling uncertainty around the change in the ensemble mean varies from case to case and in some cases is large. We compare two model-averaging methods that take the uncertainty in the change in the ensemble mean into account in the distribution fitting process. They both involve fitting distributions to the ensemble using an uncertainty-adjusted value for the ensemble mean in an attempt to increase predictive skill relative to using the unadjusted ensemble mean. We use the two methods to make projections of future rainfall based on a large data set of high-resolution EURO-CORDEX simulations for different seasons, rainfall variables, representative concentration pathways (RCPs), and points in time. Cross-validation within the ensemble using both point and probabilistic validation methods shows that in most cases predictions based on the adjusted ensemble means show higher potential accuracy than those based on the unadjusted ensemble mean. They also perform better than predictions based on conventional Akaike model averaging and statistical testing. The adjustments to the ensemble mean vary continuously between situations that are statistically significant and those that are not. Of the two methods we test, one is very simple, and the other is more complex and involves averaging using a Bayesian posterior. The simpler method performs nearly as well as the more complex method.

Improving the Potential Accuracy and Usability of EURO-CORDEX Estimates of Future Rainfall Climate using Mean Squared Error Model Averaging

Probabilities of future climate states can be estimated by fitting distributions to the members of an ensemble of climate model projections. The change in the ensemble mean can be used as an estimate of the unknown change in the mean of the distribution of the climate variable being predicted. However, the level of sampling uncertainty around the change in the ensemble mean varies from case to case and in some cases is large. We compare two model averaging methods that take the uncertainty in the change in the ensemble mean into account in the distribution fitting process. They both involve fitting distributions to the ensemble using an uncertainty-adjusted value for the ensemble mean in an attempt to increase predictive skill relative to using the unadjusted ensemble mean. We use the two methods to make projections of future rainfall based on a large dataset of high resolution EURO-CORDEX simulations for different seasons, rainfall variables, RCPs and points in time. Cross-validation within the ensemble using both point and probabilistic validation methods shows that in most cases predictions based on the adjusted ensemble means show higher potential accuracy than those based on the unadjusted ensemble mean. They also perform better than predictions based on conventional Akaike model averaging and statistical testing. The adjustments to the ensemble mean vary continuously between situations that are statistically significant and those that are not. Of the two methods we test, one is very simple, and the other is more complex and involves averaging using a Bayesian posterior. The simpler method performs nearly as well as the more complex method.

ON POTENTIAL ACCURACY OF ONBOARD LIDAR-THERMAL CONTROL OF UNDERGROUND PIPELINE LAY-OUT ROUTE

Carrying out of systematic control of oil and gas pipeline condition is important for provision of normal operability of hydrocarbon transporting system. Implementation of monitoring of pipelines condition using traditional methods requires a lot of material and labour resources. The most important alternative is utilization of unmanned aerial vehicles equipped by lidar. The accident at the pipeline may occur due to such causes as leak, rupture, denture, other causes and unknown ones. The potential accuracy of suggested method for lidar-thermal remote control of route of underground pipeline lay out is analyzed. The possibility for increasing of accuracy of identification of underground pipelines by way of decrease error of identification on two signatures is considered. The chosen signatures are geometrical coordinate at the horizontal plane defined by thermal sensing and vertical coordinate determined by laser measurements. It is determined that by cause of hydromechanical processes occurred in soil within imits of route the shift of pipeline and increase of soil layer level over the pipeline take place. These effects form the total uncertainty of determination of accurate coordinates of pipeline from the board of carrier of laser and thermal sensor. It is shown that performed optimization allows to increase the geometrical accuracy of route determination using suggested method of laser-thermal sensing.

On the experiment validity of the continuous medium motion detection by the waveguide method

Electronic intelligence is an important element of electronic warfare, which «is not announced and never stops». The purpose of electronic reconnaissance is to detect the emitting radio-electronic means of a potential enemy, to determine its location and radiation parameters using passive (non-emitting equipment). Electronic warfare, even in peacetime, is a promising area of development. The use of passive methods allows work to be carried out covertly, without detection. The peculiarity of the proposed method is that a priori information about the objects that reflected the signal is not required. Determination of the coordinates of the emitter is carried out by determining the delay between the arrival of the direct signal and the set of reflections from the terrain. The use of detailed, for today, satellite maps of the terrain allow with some accuracy to determine the coordinates of reflecting objects on the ground. The coordinates of the receiving point can also be determined with high accuracy using global navigation systems. The data entered the computer and the recording of signals obtained as a result of observing the air allows us to determine the coordinates of the radio emission source. The algorithm proposed in the article allows reducing the number of receiving points to one and using a phase direction finder to determine the direction of signal arrival. Evaluation of the potential accuracy of the method showed the possibility of practical application, while better results can be obtained when improving the algorithm in terms of improving the algorithms for determining the times of arrival of signals, algorithms for their extraction and post-processing of experimental data.

MITIGATING IMAGE RESIDUALS SYSTEMATIC PATTERNS IN UNDERWATER PHOTOGRAMMETRY

Systematic errors may result from the adoption of an incomplete functional model that is not able to properly incorporate all the effects involved in the image formation process. These errors very likely appear as systematic residual patterns in image observations and produce deformations of the photogrammetric model in object space. The Brown/Beyer model of self-calibration is often adopted in underwater photogrammetry, although it does not take into account the refraction introduced by the passage of the optical ray through different media, i.e. air and water. This reduces the potential accuracy of photogrammetry underwater. In this work, we investigate through simulations the depth-dependent systematic errors introduced by unmodelled refraction effects when both flat and dome ports are used. The importance of camera geometry to reduce the deformation in the object space is analyzed and mitigation measures to reduce the systematic patterns in image observations are investigated. It is shown how, for flat ports, the use of a stochastic approach, consisting in radial weighting of image observations, improves the accuracy in object space up to 50%. Iterative look-up table corrections are instead adopted to reduce the evident systematic residual patterns in the case of dome ports.

Space radar terrain survey and the joint flight of a spacecraft pair

The paper considers the concept of space radar monitoring complex performing Earth observation by two spacecrafts according to the technology of synthesized aperture in an interferometry scheme that allows obtaining a global high-precision digital model of the Earth’s relief. The first key problem when creating the complex is the development of an algorithm for determining the heights of the resulting image relative to the relativity surface. Unlike the traditional interferometer scheme using angular coordinates, radar gives the current coordinates of all points involved in the measurement scheme. This allows new algorithm using the difference between two space phase measurements of the downrange to the same surface element to be proposed. Both measurements are performed from two points of common position, spaced apart and representing the interferometry base. As a result, a simple estimate of the potential accuracy of altitude measurement and conditions of its implementation required for the structural scheme of space interferometry are obtained. The second key problem is the arranging coordinated kinematics of the flight of two spacecrafts, forming the base of the space interferometer with the orientation and dimensions that provide the necessary accuracy of altitude measurement. It is shown that both problems are systemically interrelated and the selection of principal solutions to optimize the complex as a whole requires simultaneous consideration and interdisciplinary coordination of the requirements determined by the specifics of each of the two problems. The technique for preliminary project evaluation of results obtained from the orbital group, visually representing all the relationships between individual characteristics of key problem areas of the complex and output target indicators of its work is proposed. The characteristics of the passive flight of spacecraft pair and the conditions for the obtaining high-quality interferometer measurement are considered. It is shown that these conditions are ensured only for a certain part of the orbit, resulting in decreasing efficiency of using the orbital group flight time, and the global survey of the planet relief takes about a year. In this context the possibility of using a small radial thrust applied for a long enough time exceeding a day is shown. As a result, the measurement conditions are stabilized, and the duration of the global survey of the planet relief is reduced to a few months. In addition, the efficiency of using the flight time of the orbital group increases, which allows performing Earth sounding using other possible programs.