Pedestrian detection with high-resolution event camera

Despite the dynamic development of computer vision algorithms, the implementation of perception and control systems for autonomous vehicles such as drones and self-driving cars still poses many challenges. A video stream captured by traditional cameras is often prone to problems such as motion blur or degraded image quality due to challenging lighting conditions. In addition, the frame rate - typically 30 or 60 frames per second - can be a limiting factor in certain scenarios. Event cameras (DVS -- Dynamic Vision Sensor) are a potentially interesting technology to address the above mentioned problems. In this paper, we compare two methods of processing event data by means of deep learning for the task of pedestrian detection. We used a representation in the form of video frames, convolutional neural networks and asynchronous sparse convolutional neural networks. The results obtained illustrate the potential of event cameras and allow the evaluation of the accuracy and efficiency of the methods used for high-resolution (1280 x 720 pixels) footage.Comment: Accepted for the PP-RAI'2023 - 4th Polish Conference on Artificial Intelligenc

Alpha-2-antiplasmin Arg407Lys polymorphism and cryptogenic ischemic cerebrovascular events: Association with neurological deficit

Objective Genetic background of cryptogenic ischemic stroke (IS) and transient ischemic attack (TIA) remains uncertain. Alpha-2-antiplasmin (α2AP) Arg407Lys polymorphism has been shown to be less common in patients with abdominal aortic aneurysm (AAA) compared with healthy controls. We investigated associations of α2AP Arg407Lys polymorphism with cryptogenic IS and TIA. Methods We studied 165 consecutive Caucasian patients who experienced cryptogenic IS (n=123) or TIA (n=42). Neurological outcomes were assessed using the modified Rankin Scale (mRS) in the acute phase of cerebral ischemia and 8 (6–12) months after the index episode. Patients were genotyped for α2AP Arg407Lys polymorphism (rs1057335) using real time PCR technique. Results The allele frequency of Arg407Lys polymorphism was: 0.82/0.18. The 407Lys allele was more frequent in TIA patients compared to the IS group (0.29 vs. 0.14, p=0.003). In the whole group, as well as in IS and TIA patients analyzed separately, possession of the 407Lys allele was associated with excellent outcome (mRS 0–1) during follow-up (p<0.05) but not in the acute phase of ischemic events both in thrombolyzed and nonthrombolyzed IS patients. The multivariate logistic regression model showed that the excellent outcome (mRS 0–1) assessed after 8 (6–12) months since the index cerebral ischemia was predicted by the occurrence of Lys407 allele (OR 6.18, 95% CI, 2.01–18.98, p=0.001). Conclusion The presence of 407Lys allele is associated with better prognosis in cryptogenic cerebrovascular events. Our findings suggest that the α2AP Arg407Lys polymorphism could be involved in the pathogenesis of cerebral ischemia and its outcomes

Effect of rapid solidification aluminum alloys with different Si content on mechanical properties and microstructure

Rapid solidification is a relatively new and effective way of ultrafine grained UFG aluminum alloys production with enhanced mechanical properties. Due to significant cooling rate close to almost 106 K/s it is possible to obtain material with grain size far below 100 nm. In the present study RS aluminum alloys with Si content in a range of 5-10 wt.% were produced during melt spinning. As a result, materials in a form of ribbons were produced. As-received flakes were subjected to cold pressing into a cylindrical billets with diameter of 40 mm. Hot extrusion of pre-compacted material was subsequently performed at the temperature of 450 °C with press ram speed of 3 mm/s and extrusion ratio of λ=25. In this work influence of brittle phases on mechanical properties of as-extruded rods will be examined. Both tensile and microhardness tests were performed in order to determine mechanical properties of obtained profiles. It has been showed that brittle phases refinement during melt spinning significantly influences mechanical properties of tested materials

SELECTION OF OPTIMAL CONDITIONS FOR SOLID BONDING OF THE AlSi11 ALUMINIUM ALLOY

In the present work, the optimal conditions for solid bonding of fragmented aluminum alloy were determined. The research was conducted on metal chips from the AlSi11 TM aluminum alloy after the turning process. The selection of proper bonding conditions was based on the results of tensile tests and surface quality analysis of as-extruded profiles. The extrusion process was conducted within a temperature range of 350–500°C, with a ram speed of 13 mm/s. Extrusion ratio λ was 25. As a reference material, a sample from the solid AlSi11IM alloy has been extruded under the same conditions.The influence of temperature during direct extrusion on both maximum force and surface quality of obtained profiles has been determined. With reference to tensile test results, no significant influence of temperature on the mechanical properties has been noticed. Profiles extruded at 500°C were characterized by visible cracks on the surface, oriented perpendicular in the direction of extrusion. Moreover, surface flaws were also noticed in profiles extruded at 350°C. A tensile testrevealed a strong relationship between the extrusion conditions and plasticity of solid bonded rods. A shiny and smooth surface was obtained only in profiles extruded at a temperature range of 400–450°C.Selection of optimal conditions for solid bonding of the AlSi11 aluminium allo

Optimum experimental designs for models with a skewed error distribution : with an application to stochastic frontier models

In this thesis, optimum experimental designs for a statistical model possessing a skewed error distribution are considered, with particular interest in investigating possible parameter dependence of the optimum designs. The skewness in the distribution of the error arises from its assumed structure. The error consists of two components (i) random error, say V, which is symmetrically distributed with zero expectation, and (ii) some type of systematic error, say U, which is asymmetrically distributed with nonzero expectation. Error of this type is sometimes called 'composed' error. A stochastic frontier model is an example of a model that possesses such an error structure. The systematic error, U, in a stochastic frontier model represents the economic efficiency of an organisation. Three methods for approximating information matrices are presented. An approximation is required since the information matrix contains complicated expressions, which are difficult to evaluate. However, only one method, 'Method 1', is recommended because it guarantees nonnegative definiteness of the information matrix. It is suggested that the optimum design is likely to be sensitive to the approximation. For models that are linearly dependent on the model parameters, the information matrix is independent of the model parameters but depends on the variance parameters of the random and systematic error components. Consequently, the optimum design is independent of the model parameters but may depend on the variance parameters. Thus, designs for linear models with skewed error may be parameter dependent. For nonlinear models, the optimum design may be parameter dependent in respect of both the variance and model parameters. The information matrix is rank deficient. As a result, only subsets or linear combinations of the parameters are estimable. The rank of the partitioned information matrix is such that designs are only admissible for optimal estimation of the model parameters, excluding any intercept term, plus one linear combination of the variance parameters and the intercept. The linear model is shown to be equivalent to the usual linear regression model, but with a shifted intercept. This suggests that the admissible designs should be optimal for estimation of the slope parameters plus the shifted intercept. The shifted intercept can be viewed as a transformation of the intercept in the usual linear regression model. Since D_A-optimum designs are invariant to linear transformations of the parameters, the D_A-optimum design for the asymmetrically distributed linear model is just the linear, parameter independent, D_A-optimum design for the usual linear regression model with nonzero intercept. C-optimum designs are not invariant to linear transformations. However, if interest is in optimally estimating the slope parameters, the linear transformation of the intercept to the shifted intercept is no longer a consideration and the C-optimum design is just the linear, parameter independent, C-optimum design for the usual linear regression model with nonzero intercept. If interest is in estimating the slope parameters, and the shifted intercept, the C-optimum design will depend on (i) the design region; (ii) the distributional assumption on U; (iii) the matrix used to define admissible linear combinations of parameters; (iv) the variance parameters of U and V; (v) the method used to approximate the information matrix. Some numerical examples of designs for a cross-sectional log-linear Cobb-Douglas stochastic production frontier model are presented to demonstrate the nonlinearity of designs for models with a skewed error distribution. Torsney's (1977) multiplicative algorithm was implemented in finding the optimum designs.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Editing, Streaming and Playing of MPEG-4 Facial Animations

Computer animated faces have found their way into a wide variety of areas. Starting from entertainment like computer games, through television and films to user interfaces using “talking heads”. Animated faces are also becoming popular in web applications in form of human-like assistants or newsreaders. This thesis presents a few aspects of dealing with human face animations, namely: editing, playing and transmitting such animations. It describes a standard for handling human face animations, the MPEG-4 Face Animation, and shows the process of designing, implementing and evaluating applications compliant to this standard. First, it presents changes introduced to the existing components of the Visage|toolkit package for dealing with facial animations, offered by the company Visage Technologies AB. It also presents the process of designing and implementing of an application for editing facial animations compliant to the MPEG-4 Face Animation standard. Finally, it discusses several approaches to the problem of streaming facial animations over the Internet or the Local Area Network (LAN)

Micro Unmanned Aerial Vehicle Visual Servoing for Cooperative Indoor Exploration.

Abstract—Recent advances in the field of Micro Unmanned Aerial Vehicles (MAVs) make flying robots of small dimensions suitable platforms for performing advanced indoor missions. In order to achieve autonomous indoor flight a pose estimation technique is necessary. This paper presents a complete system which incorporates a vision-based pose estimation method to allow a MAV to navigate in indoor environments in cooperation with a ground robot. The pose estimation technique uses a lightweight Light Emitting Diode (LED) cube structure as a pattern attached to a MAV. The pattern is observed by a ground robot’s camera which provides the flying robot with the estimate of its pose. The system is not confined to a single location and allows for cooperative exploration of unknown environments. It is suitable for performing missions of a search and rescue nature where

Hastily formed knowledge networks and distributed situation awareness for collaborative robotics

In the context of collaborative robotics, distributed situation awareness is essential for  supporting collective intelligence in teams of robots and human agents where it can be used for both individual and collective decision support. This is particularly important in applications pertaining to emergency rescue and crisis management. During operational missions, data and knowledge are gathered incrementally and in different ways by heterogeneous robots and humans. We describe this as the creation of Hastily Formed Knowledge Networks (HFKNs). The focus of this paper is the specification and prototyping of a general distributed system architecture that supports the creation of HFKNs by teams of robots and humans. The information collected ranges from low-level sensor data to high-level semantic knowledge, the latter represented in part as RDF Graphs. The framework includes a synchronization protocol and associated algorithms that allow for the automatic distribution and sharing of data and knowledge between agents. This is done through the distributed synchronization of RDF Graphs shared between agents. High-level semantic queries specified in SPARQL can be used by robots and humans alike to acquire both knowledge and data content from team members. The system is empirically validated and complexity results of the proposed algorithms are provided. Additionally, a field robotics case study is described, where a 3D mapping mission has been executed using several UAVs in a collaborative emergency rescue scenario while using the full HFKN Framework.Funding Agencies|ELLIIT Network Organization for Information and Communication Technology, Sweden (Project B09) and the Swedish Foundation for Strategic Research SSF (Smart Systems Project RIT15-0097). The first author is also supported by an RExperts Program Grant 2020A1313030098 from the Guangdong Department of Science and Technology, China in addition to a Sichuan Province International Science and Technology Innovation Cooperation Project Grant 2020YFH0160.</p

Sustainable Management of Calcite Contaminated with Waste Toner Powder in the Construction Industry

Due to the highly explosive nature of toners, absorbers are used in toner processing plants to prevent the explosion of toner dust suspension in the air. Usually, finely divided calcite (in the form of a dust) is used. The mixture of toner-calcite is treated as waste and landfilled. The main aim of this study was to investigate the possibility of using toner-contaminated calcite as an additive to concrete. Materials originating from the toner processing plant were analyzed by using TGA, AAS, XRD, FTIR and SEM techniques. Calcite-waste toner powder mixture in amounts 0%, 1%, 5%, 10%, 15% and 20% were used to produce concrete. The results of the study showed that an increase in the amount of calcite contaminated with toner to 20% causes a decrease in compressive strength of concrete by 24–51% depending on material sample. The addition of calcite in amounts up to 5% can be a suitable method of its management