Department of Electrical Engineering (ISY)

We present a method to estimate the time-to-impact (TTI) from a sequence of images. The method is based on detecting and tracking local extremal points. Their endurance within and between pixels is measured, accumulated, and used to achieve the TTI. This method, which improves on an earlier proposal, is entirely different from the ordinary optical flow technique and allows for fast and low-complex processing. The method is inspired by insects, which have some TTI capability without the possibility to compute high-complex optical flow. The method is further suitable for near-sensor image processing architectures. (c) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

To further develop a low-power low-cost optical motion detector for use with traffic detection under dark and daylight conditions, we have developed and verified a procedure to use a Near Sensor Image Processing (NSIP) programmable 2-D optical sensor in a "1-D mode" to achieve the effect of using a cylindrical lens, thus improving the angle-of-view (AOV), the sensitivity, and usefulness of the sensor. Using an existing 256 x 256 element sensor in an innovative way, the AOV was increased from 0.4 to 21.3 in the vertical direction while also improving the sensitivity. The details of the sensor hardware architecture are described in detail and pseudo code for programming the sensor is discussed. The results were used to demonstrate the extraction of Local Extreme Points (LEPs) used for Time-To-Impact (TTI) calculations to estimate the speed of an approaching vehicle.

A CMOS sensor chip was used, together with an Arduino microcontroller, to create and verify a low-power low-cost optical motion detector for use in traffic detection under dark and daylight conditions. The chip can sense object features with very high dynamic range. On-chip near sensor image processing was used to reduce the data to be transferred to a host computer. A method using local extrema point detection was used to estimate motion through time-to-impact (TTI). Sensor data from the headlights of an approaching/passing car were used to extract TTI values similar to estimations from distance and speed of the object. The method can be used for detection of approaching objects to switch on streetlights (dark conditions) or sensors for traffic lights instead of magnetic sensors in the streets or conventional cameras (dark and daylight conditions). A sensor with a microcontroller operating at low clock frequency will consume less than 30 mW in this application. 

The communication outposts of the emerging Internet of Things are embodied by ordinary items, which desirably include all-printed flexible sensors, actuators, displays and akin organic electronic interface devices in combination with silicon-based digital signal processing and communication technologies. However, hybrid integration of smart electronic labels is partly hampered due to a lack of technology that (de)multiplex signals between silicon chips and printed electronic devices. Here, we report all-printed 4-to-7 decoders and seven-bit shift registers, including over 100 organic electrochemical transistors each, thus minimizing the number of terminals required to drive monolithically integrated all-printed electrochromic displays. These relatively advanced circuits are enabled by a reduction of the transistor footprint, an effort which includes several further developments of materials and screen printing processes. Our findings demonstrate that digital circuits based on organic electrochemical transistors (OECTs) provide a unique bridge between all-printed organic electronics (OEs) and low-cost silicon chip technology for Internet of Things applications.

An evolvable organic electrochemical transistor (OECT), operating in the hybrid accumulation-depletion mode is reported, which exhibits short-term and long-term memory functionalities. The transistor channel, formed by an electropolymerized conducting polymer, can be formed, modulated, and obliterated in situ and under operation. Enduring changes in channel conductance, analogous to long-term potentiation and depression, are attained by electropolymerization and electrochemical overoxidation of the channel material, respectively. Transient changes in channel conductance, analogous to short-term potentiation and depression, are accomplished by inducing nonequilibrium doping states within the transistor channel. By manipulating the input signal, the strength of the transistor response to a given stimulus can be modulated within a range that spans several orders of magnitude, producing behavior that is directly comparable to short- and long-term neuroplasticity. The evolvable transistor is further incorporated into a simple circuit that mimics classical conditioning. It is forecasted that OECTs that can be physically and electronically modulated under operation will bring about a new paradigm of machine learning based on evolvable organic electronics.

A method to decorate cellulose-based helices retrieved from the plant celery with a conductive polymer is proposed. Using a layer-by-layer method, the decoration of the polyanionic conducting polymer poly(4-(2,3-dihydrothieno [3,4-b]-[1,4]dioxin-2-yl-methoxy)-1-butanesulfonic acid (PEDOT-S) is enhanced after coating the negatively charged cellulose helix with a polycationic polyethyleneimine. Microscopy techniques and two-point probe are used to image the structure and measure the conductivity of the helix. Analysis of the optical and electrical properties of the coated helix in the terahertz (THz) frequency range shows a resonance close to 1 THz and a broad shoulder that extends to 3.5 THz, consistent with electromagnetic models. Moreover, as helical antennas, it is shown that both axial and normal modes are present, which are correlated to the orientation and antenna electrical lengths of the coated helices. This work opens the possibility of designing tunable terahertz antennas through simple control of their dimensions and orientation.

Organic electrochemical transistors (OECTs) have been the subject of intense research in recent years. To date, however, most of the reported OECTs rely entirely on p-type (hole transport) operation, while electron transporting (n-type) OECTs are rare. The combination of efficient and stable p-type and n-type OECTs would allow for the development of complementary circuits, dramatically advancing the sophistication of OECT-based technologies. Poor stability in air and aqueous electrolyte media, low electron mobility, and/or a lack of electrochemical reversibility, of available high-electron affinity conjugated polymers, has made the development of n-type OECTs troublesome. Here, it is shown that ladder-type polymers such as poly(benzimidazobenzophenanthroline) (BBL) can successfully work as stable and efficient n-channel material for OECTs. These devices can be easily fabricated by means of facile spray-coating techniques. BBL-based OECTs show high transconductance (up to 9.7 mS) and excellent stability in ambient and aqueous media. It is demonstrated that BBL-based n-type OECTs can be successfully integrated with p-type OECTs to form electrochemical complementary inverters. The latter show high gains and large worst-case noise margin at a supply voltage below 0.6 V.

Vertical organic electrochemical transistors (OECTs) have been manufactured solely using screen printing. The OECTs are based on PEDOT:PSS (poly(3,4-ethylenedioxythiophene) doped with poly (styrene sulfonic acid)), which defines the active material for both the transistor channel and the gate electrode. The resulting vertical OECT devices and circuits exhibit low-voltage operation, relatively fast switching, small footprint and high manufacturing yield; the last three parameters are explained by the reliance of the transistor configuration on a robust structure in which the electrolyte vertically bridges the bottom channel and the top gate electrode. Two different architectures of the vertical OECT have been manufactured, characterized and evaluated in parallel throughout this report. In addition to the experimental work, SPICE models enabling simulations of standalone OECTs and OECT-based circuits have been developed. Our findings may pave the way for fully integrated, low-voltage operating and printed signal processing systems integrated with e.g. printed batteries, solar cells, sensors and communication interfaces. Such technology can then serve a low-cost base technology for the internet of things, smart packaging and home diagnostics applications.

The design, fabrication and operation of a range of functional power converter circuits, based on diode configured organic field-effect transistors as the rectifying unit and capable of transforming a high AC input voltage to a selectable DC voltage, are presented. The converter functionality is demonstrated by selecting and tuning its constituents so that it can effectively drive a low-voltage organic electronic device, a light-emitting electrochemical cell (LEC), when connected to high-voltage AC mains. It is established that the preferred converter circuit for this task comprises an organic full-wave rectifier and a regulation resistor but is void of a smoothing capacitor, and that such a circuit connected to the AC mains (230 V, 50 Hz) successfully can drive an LEC to bright luminance (360 cd m(-2)) and high efficiency (6.4 cd A(-1)). (C) 2017 Elsevier B.V. All rights reserved.

A simplified model is developed to understand the field and potential distribution through devices based on a ferroelectric film in direct contact with an electrolyte. Devices based on the ferroelectric polymer polyvinylidenefluoride-trifluoroethylene (PVDF-TrFE) were produced – in metalferroelectric-metal, metal-ferroelectric-dielectric-metal, and metal-ferroelectric-electrolyte-metal architectures – and used to test the model, and simulations based on the model and these fabricated devices were performed. From these simulations we find indication of progressive polarization of the films. Furthermore, the model implies that there is a relation between the separation of charge within the devices and the observed open circuit voltage. This relation is confirmed experimentally. The ability to polarize ferroelectric polymer films through aqueous electrolytes, combined with the strong correlation between the properties of the electrolyte double layer and the device potential, opens the door to a variety of new applications for ferroelectric technologies, e.g., regulation of cell culture growth and release, steering molecular self-assembly, or other large area applications requiring aqueous environments.

Elastic optical networking (EON) with space-division multiplexing (SDM) is the only evident long-term solution to the capacity needs of the future networks. The introduction of space via spatial fibers, such as multicore fibers (MCF) to EON provides an additional dimension as well as challenges to the network planning and resource optimization problem. There are various types of technologies for SDM transmission medium, switching, and amplification; each of them induces different capabilities and constraints on the network. For example, employing MCF as the transmission medium for SDM mitigates the spectrum continuity constraint of the routing and spectrum allocation problem for EON. In fact, cores can be switched freely on different links during routing of the network traffic. On the other hand, intercore crosstalk should be taken into account while solving the resource allocation problem. In the framework of switching for elastic SDM network, the programmable architecture on demand (AoD) node (optical white box) can provide a more scalable solution with respect to the hard-wired reconfigurable optical add/drop multiplexers (ROADMs) (optical black box). This study looks into the routing, modulation, spectrum, and core allocation (RMSCA) problem for weakly-coupled MCF-based elastic SDM networks implemented through AoDs and static ROADMs. The proposed RMSCA strategies integrate the spectrum resource allocation, switching resource deployment, and physical layer impairment in terms of intercore crosstalk through a multiobjective cost function. The presented strategies perform a cross-layer optimization between the network and physical layers to compute the actual intercore crosstalk for the candidate resource solutions and are specifically tailored to fit the type of optical node deployed in the network. The aim of all these strategies is to jointly optimize the switching and spectrum resource efficiency when provisioning demands with diverse capacity requirements. Extensive simulation results demonstrate that 1) by exploiting the dense intranodal connectivity of the ROADM-based SDM network, resource efficiency and provisioned traffic volume improve significantly related to the AoD-based solution, 2) the intercore crosstalk aware strategies improve substantially the provisioned traffic volume for the AoD-based SDM network, and 3) the switching modules grows very gently for the network designed with AoD nodes related to the one with ROADMs as the traffic increases, qualifying AoD as a scalable and cost-efficient choice for future SDM networks.

n/a

We describe a method for eye pupil localization based on an ensemble of randomized regression trees and use several publicly available datasets for its quantitative and qualitative evaluation. The method compares well with reported state-of-the-art and runs in real-time on hardware with limited processing power, such as mobile devices.

Optical networks are expected to provide a unified platform for a diverse set of emerging applications (three-dimensional TV, digital cinema, e-health, grid computing, etc). The service differentiation will be an essential feature of these networks. Considering the fact that users have different levels of patience for different network applications, referred to as set-up delay tolerance, it will be one of the key parameters for service differentiation. Service differentiation based on set-up delay tolerance will not only enable network users to select an appropriate service class (SC) in compliance with their requirements, but will also provide an opportunity to optimize the network resource provisioning by exploiting this information, resulting in an improvement in the overall performance. Improvement in network performance can be further enhanced by exploiting the connection holding-time awareness. However, when multiple classes of service with different set-up delay tolerances are competing for network resources, the connection requests belonging to SCs with higher set-up delay tolerance have better chances to grab the resources and leave less room for the others, resulting in degradation in the blocking performance of less patient customers. This study proposes different scheduling strategies for promoting the requests belonging to smaller set-up delay tolerance SCs, such as giving priority, reserving some fraction of available resources, and augmenting the research space by providing some extra paths. Extensive simulation results show that 1) priority in the rescheduling queue is not always sufficient for eradicating the degradation effect of high delay tolerant SCs on the provisioning rate of the most stringent SC, and 2) by utilizing the proposed strategies, resource efficiency and overall network blocking performance improve significantly in all SCs.

We present a method suitable for a time-to-impact sensor. Inspired by the seemingly "low" complexity of small insects, we propose a new approach to optical flow estimation that is the key component in time-to-impact estimation. The approach is based on measuring time instead of the apparent motion of points in the image plane. The specific properties of the motion field in the time-to-impact application are used, such as measuring only along a one-dimensional (1-D) line and using simple feature points, which are tracked from frame to frame. The method lends itself readily to be implemented in a parallel processor with an analog front-end. Such a processing concept [near-sensor image processing (NSIP)] was described for the first time in 1983. In this device, an optical sensor array and a low-level processing unit are tightly integrated into a hybrid analog-digital device. The high dynamic range, which is a key feature of NSIP, is used to extract the feature points. The output from the device consists of a few parameters, which will give the time-to-impact as well as possible transversal speed for off-centered viewing. Performance and complexity aspects of the implementation are discussed, indicating that time-to-impact data can be achieved at a rate of 10 kHz with todays technology.

Precise control over processing, transport and delivery of ionic and molecular signals is of great importance in numerous fields of life sciences. Integrated circuits based on ion transistors would be one approach to route and dispense complex chemical signal patterns to achieve such control. To date several types of ion transistors have been reported; however, only individual devices have so far been presented and most of them are not functional at physiological salt concentrations. Here we report integrated chemical logic gates based on ion bipolar junction transistors. Inverters and NAND gates of both npn type and complementary type are demonstrated. We find that complementary ion gates have higher gain and lower power consumption, as compared with the single transistor-type gates, which imitates the advantages of complementary logics found in conventional electronics. Ion inverters and NAND gates lay the groundwork for further development of solid-state chemical delivery circuits.

Electrolyte-gated organic thin-film transistors (OTFTs) can offer a feasible platform for future flexible, large-area and low-cost electronic applications. These transistors can be divided into two groups on the basis of their operation mechanism: (i) field-effect transistors that switch fast but carry much less current than (ii) the electrochemical transistors which, on the contrary, switch slowly. An attractive approach would be to combine the benefits of the field-effect and the electrochemical transistors into one transistor that would both switch fast and carry high current densities. Here we report the development of a polyelectrolyte-gated OTFT based on conjugated polyelectrolytes, and we demonstrate that the OTFTs can be controllably operated either in the field-effect or the electrochemical regime. Moreover, we show that the extent of electrochemical doping can be restricted to a few monolayers of the conjugated polyelectrolyte film, which allows both high current densities and fast switching speeds at the same time. We propose an operation mechanism based on self-doping of the conjugated polyelectrolyte backbone by its ionic side groups.

A cell lineage is the ancestral relationship between a group of cells that originate from a single founder cell. For example, in the embryo of the nematode Caenorhabditis elegans an invariant cell lineage has been traced, and with this information at hand it is possible to theoretically model the emergence of different cell types in the lineage, starting from the single fertilized egg. In this report we outline a modelling technique for cell lineage trees, which can be used for the C. elegans embryonic cell lineage but also extended to other lineages. The model takes into account both cell-intrinsic (transcription factor-based) and -extrinsic (extracellular) factors as well as synergies within and between these two types of factors. The model can faithfully recapitulate the entire C. elegans cell lineage, but is also general, i.e., it can be applied to describe any cell lineage. We show that synergy between factors, as well as the use of extrinsic factors, drastically reduce the number of regulatory factors needed for recapitulating the lineage. The model gives indications regarding co-variation of factors, number of involved genes and where in the cell lineage tree that asymmetry might be controlled by external influence. Furthermore, the model is able to emulate other (Boolean, discrete and differential-equation-based) models. As an example, we show that the model can be translated to the language of a previous linear sigmoid-limited concentration-based model (Geard and Wiles, 2005). This means that this latter model also can exhibit synergy effects, and also that the cumbersome iterative technique for parameter estimation previously used is no longer needed. In conclusion, the proposed model is general and simple to use, can be mapped onto other models to extend and simplify their use, and can also be used to indicate where synergy and external influence would reduce the complexity of the regulatory process.

A conventional desktop inkjet printer has been used as a combined deposition and patterning tool of electrochemical organic transistors on rough flexible carriers. The functionality of these devices rely upon redox reactions occurring at the interface between a conjugated polymer film and an electrolyte. Both the electrolyte and the conjugated polymer suspension (an aqueous dispersion of poly(3,4-ethylenedioxythiophene):poly(styrene sulphonic acid)) were additively patterned with the inkjet printer, making the electrochemical device all-inkjet printed. Basic implementations of the transistor in simple electrochemical logical circuitry have been produced. The printing technique can be anticipated to be used for the production of small series of devices based on the electrochemical technology discussed. © 2008 Elsevier B.V. All rights reserved.

Using organic electrochemical transistors as sensors, the sample-receptor reaction often induces moderate changes only in the drain current dynamics as the gate voltage level is switched. Here, we report an electrochemical sensor circuit including electrochemical transistors based on poly(3,4-ethylenedioxythiophene) doped with polystyrenesulfonate that puts out a static sensor response signal. The circuit includes a sample and a reference transistor that are both driven in the resistive mode at 0.1 V. Measurements were performed on aqueous salt electrolytes ranging from 100 to 500 mM concentrations. The signal-ON sensor circuit provides a tenfold increase in the sensitivity as compared to single transistor sensors.

The use of organic polymers for electronic functions is mainly motivated by the low-end applications, where low cost rather than advanced performance is a driving force. Materials and processing methods must allow for cheap production. Printing of electronics using inkjets¹ or classical printing methods has considerable potential to deliver this. Another technology that has been around for millennia is weaving using fibres. Integration of electronic functions within fabrics, with production methods fully compatible with textiles, is therefore of current interest, to enhance performance and extend functions of textiles². Standard polymer field-effect transistors require well defined insulator thickness and high voltage³, so they have limited suitability for electronic textiles. Here we report a novel approach through the construction of wire electrochemical transistor (WECT) devices, and show that textile monofilaments with 10–100 µm diameters can be coated with continuous thin films of the conducting polythiophene poly(3,4-ethylenedioxythiophene), and used to create micro-scale WECTs on single fibres. We also demonstrate inverters and multiplexers for digital logic. This opens an avenue for three-dimensional polymer micro-electronics, where large-scale circuits can be designed and integrated directly into the three-dimensional structure of woven fibres.

This paper presents new methods for use of dense motion fields for motion compensation of interlaced video. The motion estimation is based on previously decoded field-images. The motion is then temporally predicted and used for motion compensated prediction of the field-image to be coded. The motion estimation algorithm is phase-based and uses two or three field-images to achieve motion estimates with sub-pixel accuracy. To handle non-constant motion and the specific characteristics of the field-image to be coded, the initially predicted image is refined using forward motion compensation, based on block-matching. Tests show that this approach achieves higher PSNR than forward block-based motion estimation, when coding the residual with the same coder. The subjective performance is also better.

This paper presents a hierarchical interconnect architecture for optical data center networks composed of specially designed couplers allowing for significant reduction of required spectral resources. © OSA 2017.

We present a current supply, comprising a single organic thin-film transistor (OTFT), for the charging of supercapacitors. The current supply takes power from the electric grid (115 V AC, US standard), converts the AC voltage to a quasi-constant DC current (similar to 0.1 mA) regardless of the impedance of the load, and charges the supercapacitor. Solution-processed OTFTs based on the popular polymeric semiconductor poly(3-hexylthiophene- 2,5-diyl) have been developed to rectify the 115 V AC voltage. A diodeconfigured OTFT was used as a half-wave rectifier. The single OTFT current supply was demonstrated to charge a 220 mF supercapacitor to 1 V directly using 115 V AC voltage as the input. This work paves the road towards all-printable supercapacitor energy-storage systems with integrated chargers, which enable direct charging from a power outlet.

Architecture on demand (AoD) node offers considerable flexibility against traditional ROADMs. The paper presents a cost-efficient network planning strategy that exploits the flexibility inherent in AoD. Results show that AoD can save significantly in node modules through a proper network design.

Survivable synthetic ROADMs are equipped with redundant switching modules to support failure recovery. The paper proposes a dynamic connection provisioning strategy which exploits these idle redundant modules to provision regular traffic resulting in a substantial improvement in the blocking performance.

Space division multiplexing (SDM) over multi-core fiber (MCF) is advocated as a promising technology to overcome the capacity limit of the current single-core optical networks. However, employing the MCF for flexgrid networks necessitates the development of new concepts, such as routing, spectrum and core allocation (RSCA) for traffic demands. The introduction of MCF in the networks mitigates the spectrum continuity constraint of the routing and spectrum assignment (RSA) problem. In fact cores can be switched freely on different links during routing of the network traffic. Similarly, the route disjointness for demands with same allocated spectrum diminishes to core disjointness at the link level. On the other hand, some new issues such as the inter-core crosstalk should be taken into account while solving the RSCA problem. This paper formulates the RSCA network planning problem using the integer linear programming (ILP) formulation. The aim is to optimally minimize the maximum number of spectrum slices required on any core of MCF of a flexgrid SDM network. Furthermore, a scalable and effective heuristic is proposed for the same problem and its performance is compared with the optimal solution. The results show that the proposed algorithm is able to well approximate the optimal solution based on ILP model.

We propose a connection provisioning strategy in dynamic all-optical networks, which exploit the possibility to allow a tolerable signal quality degradation during a small fraction of holding-time resulting in a significant improvement of blocking performance.

A terminal charge and capacitance model is developed for transient behavior simulation of electrolyte-gated organic field effect transistors (EGOFETs). Based on the Ward-Dutton partition scheme, the charge and capacitance model is derived from our drain current model reported previously. The transient drain current is expressed as the sum of the initial drain current and the charging current, which is written as the product of the partial differential of the terminal charges with respect to the terminal voltages and the differential of the terminal voltages upon time. The validity for this model is verified by experimental measurements.

With the emergence of bandwidth intensive applications new methodologies need to be developed for improvement of network blocking performance, without supplying extra resources in dynamic wavelength-division-multiplexing (WDM) networks. Rerouting is one among the viable and cost-effective solutions to reduce the blocking probability (BP) of optical WDM networks. Similarly, set-up delay tolerance, a metric of service level agreement (SLA) has been exploited in [1]-[3] for improvement in network BP. In this paper, we study the rerouting in dynamic WDM network and analyze two different lightpath rerouting strategies. Moreover, we investigate further improvement in network BP by exploiting these rerouting techniques for network provisioned with set-up delay tolerance. Through extensive simulation studies, we confirm that the rerouting strategies decrease the BP substantially for network provisioned with set-up delay tolerance, even for smaller set-up delay tolerance value i.e. when the connection requests are impatient to wait for provisioning in the network. However, it also reduce BP significantly even when the network is not provisioned with set-up delay tolerance.

strategies. First we analyze a strategy which effectively utilizes two Service Level Agreement (SLA) metrics i.e. holding-time combined with set-up delay tolerance, for connection provisioning. We investigate its performance improvement compared to the scheme proposed in [4] and with the strategy which exploits only the set-up delay tolerance for connection provisioning. Secondly, we evaluate the performance of the various approaches for network blocking reduction over a wide range of network loads. Our aim is to obtain an insight information, that can be useful for selection of an optimal strategy for designing a network, with specific network parameters and performance requirements.

We present a methodology to extract parameters for an electrolyte-gated organic field effect transistor DC model. The model is based on charge drift/diffusion transport under electric field and covers all regimes. Voltage dependent capacitance, mobility, contact resistance and threshold voltage shift are taken into account in this model. The feature parameters in the model are simply extracted from the transfer or output characteristics of electrolyte-gated organic field effect transistors. The extracted parameters are verified by good agreements between experimental and simulated results.

It has long been argued that the best-effort strategy on which Internet is based will limit its use for real-time applications such as video or telephony. However, it has been shown that such services can indeed tolerate some jitter and rate variations through various error resilience and concealment techniques. Despite of that the Internet infrastructure is continuously upgraded with higher performance components, which further reduce the transmission problems; still there are certain classes of applications that undoubtedly will need new transmission paradigms. An example is the remote control of an industrial process that may require jitter levels down to a few microseconds. Another example is quantum cryptography where an optical transparent path between sender and receiver is to be established. In this paper we present a concept based on an optical overlay network infrastructure. This network concept can be applied in an incremental way and will enable the current network infrastructure to handle demands with such extreme QoS requirements.

We introduce theconcept of mobility-based communication in ad hoc networks, meaningthat the packet transport is performed mainly by the nodes'movement. We outline a model for such networks, utilizing astochastic model for the geographical location of the nodes. A testcase is defined in which three strategies for packet forwarding arepresented and evaluated.

Video generates a rich set of image information and often the useful information is only a very limited set of the available information. Another well-known fact is that visually reviewing of long video recordings is a time demanding task. In combination with the continuously increasing number of video surveillance systems, this leads to an increasing need for automated analysis of long image sequences. The goal for this work is to develop and evaluate a method for automatic detection and tracking of events recorded onto a surveillance video, such as appearance of persons or vehicles in a surveyed area, to evaluate the usefulness for forensic applications and real time applications. One core problem is the fact that both the background and the objects move, where only the physical motion of moving objects are of interest and needs to be separated from the camera motion. Another core problem in many of the video processing algorithms is parameter estimation despite invariance for accurate modeling of the desired features. Varying scale, color, lightning conditions and occlusion of the object of interest can for example cause invariance. The technical approaches for this work is to separate global and local motion by analyzing the optical flow constraints. To overcome the problem caused by such feature and object invariance, all pixels are considered independently and no feature parameters are needed. If the basic optical flow constraint is satisfied, the motion is classified as global motion. If not, the motion is considered caused by local motion, noise or other phenomena. An object that undergoes local motion can then be detected and tracked as is forms a trace in the temporal domain, while the noise appears on an intermittent basis and will be disregarded. The results from applying this method on several image sequences were compared and the robustness and ability to deal with invariance has been evaluated. The result clearly shows that in realistic situations, where visual reviewing can be quite a difficult task, computer based methods for automatic detection are useful to detected moving objects in long video recordings.

The goal of COMPUTER SECURITY 1981 is to prediet the demand for protection of eleetronic data processing (EDP) and for the information processed. To predict the future demands on computer security we have discussed the issue with several people involved in one way or another with EDP. These discussions, our own knowledge other background material have been the material for discussions amongst the authors. The results are divided into two parts. In the first part (section 4) we have been as objective as possible. In the latter part (section 5) we have discussed the differences between the results in section 4 and our own opinion as proffessional researchers.

In addition the report covers a summary of how EDP is used 1981 and a section describing the structure of the security field (which we have used in the interviews) and an outline of the investigation.