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  • 5251. Hult, Tommy
    Novel Applications of Space-Time Processing for Wireless Systems2006Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Space-time processing techniques have emerged as one of the most promising areas of research and development in wireless communications. Space-time processing signifies the signal processing performed on a system consisting of several antenna elements, whose signals are processed adaptively in order to exploit both the spatial (space) and temporal (time) dimensions of the radio channel. Space-time processing techniques can be applied at the transmitter, the receiver or both. The use of space-time signal processing can significantly improve average signal power, mitigating fading, and reduce inter-symbol interference and co-channel interference. This can significantly improve capacity, coverage and quality of wireless systems. In this thesis we expand the scope of space-time processing by proposing novel applications in wireless communications. These include the reduction of possibly harmful electromagnetic radiation from mobile phones, enhancing link quality for Bluetooth links in indoor office environments, and increasing the spectral efficiency of satellite communication systems. Several studies have been conducted on the effects of radiation from hand held mobile phones. The amount of radiation emitted from most mobile phones is minute, but given the close proximity of the phone to the head it might be possible for the radiation to cause harm. In Part I, we suggest the use of adaptive signal processing algorithms combined with a MIMO (multiple-input multiple output) antenna system to decrease the electromagnetic radiation inside a certain volume in space (e.g. the the human head). In addition, we investigate the impact of MIMO antenna parameters, carrier frequency and power constraint on the performance of the system. Over the last decade there has been an explosive growth in the use of wireless mobile communications. Today we find users with mobile phones, wireless PDA's, MP3 players, and wireless headphones to connect to these devices. In Part II, we investigate the wave propagation effects of a short-range wireless device, such as the Bluethooth technology. Specifically, we assess the fading phenomenon for Bluetooth link in indoor office environment by simulation of different propagation scenarios, and use measurement results to confirm our findings. In addition, we investigate the improvement in performance resulting from receiver diversity gain of a system employing multiple receive antennas with various combining techniques. The need for high-speed, high-quality bandwidth efficient mobile communications is constantly increasing. In Part III, we address the potential gain of using MIMO antenna system in combination with OFDM (orthogonal frequency division multiplexing) in order to increase the bandwidth efficiency in satellite communication systems. In particular, we consider the increase in channel capacity that is possible by exploiting satellite and polarization diversity. In addition we investigate the effect of using different compact MIMO polarization antenna configurations and power control on the information theoretic capacity of the total transmission channel of the satellite system.

  • 5252. Hult, Tommy
    Space-Time Processing Applications for Wireless Communications2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Wireless mobile communication networks are rapidly growing at an incredible rate around the world and a number of improved and emerging technologies are seen to be critical to the improved economics and performance of these networks. The technical revolution and continuing growth of mobile radio communication systems has been made possible by extraordinary advances in the related fields of digital computing, high-speed circuit technology, the Internet and, of course, digital signal processing. Improved third generation (3G) and future generation wireless communication systems must support a substantially wider and enhanced range of services with respect to those supported by second generation and basic 3G systems. The never-ending quest for such personal and multimedia services, however, demands technologies operating at higher data rates and broader bandwidths. This combined with the unpredictability and randomness of the mobile propagation channel has created many new technically challenging problems for which innovative, adaptive and advanced signal processing techniques may offer new and better solutions. Space-time processing techniques have emerged as one of the most promising areas of research and development in wireless communications for the efficient utilization of the physical mobile radio propagation channel. Space-time processing signifies the signal processing performed on a system consisting of several antenna elements, whose signals are processed adaptively in order to exploit both the spatial (space) and temporal (time) dimensions of the radio channel. This can significantly improve the capacity, coverage, quality and energy efficiency of wireless systems. This thesis expands the scope of space-time processing by proposing novel applications in wireless communication systems. These include the reduction of possibly harmful electromagnetic radiation from mobile phones, enhancing the quality of Bluetooth links in indoor office environments, increasing the spectral efficiency of satellite and the novel high altitude platforms (HAPs) communication systems, enhancing the coverage and capacity of integrated multiple-HAP 3G systems, and improving the energy efficiency of cooperative wireless sensor networks. The performance of these systems is assessed by theoretical analysis, by computer simulations under a range of propagation environments including realistic channel models, advanced commercial electromagnetic modeling software, and a proposed novel multi-channel simulator suitable for various space-time applications.

  • 5253. Hult, Tommy
    WCDMA Uplink Interference Assessment from Multiple High Altitude Platform Configurations2008In: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. vol. 2008, no Special Issue on Advanced Communication Techniques and Applications for High-Altitude PlatformsArticle in journal (Refereed)
    Abstract [en]

    We investigate the possibility of multiple high altitude platform (HAP) coverage of a common cell area using a wideband code division multiple access (WCDMA) system. In particular, we study the uplink system performance of the system. The results show that depending on the traffic demand and the type of service used, there is a possibility of deploying 3-6 HAPs covering the same cell area. The results also show the effect of cell radius on performance and the position of the multiple HAP base stations which give the worst performance.

  • 5254. Hult, Tommy
    et al.
    Falletti, Emanuela
    Mohammed, Abbas
    Sellone, Fabrizio
    Multi-antenna Channel Model for Space-Polarization Systems2007Conference paper (Refereed)
  • 5255. Hult, Tommy
    et al.
    Falletti, Emanuela
    Mohammed, Abbas
    Sellone, Fabrizio
    The Impact of Depolarizing Effects on a Multiple HAP System Employing Polarization Diversity2007Conference paper (Refereed)
  • 5256. Hult, Tommy
    et al.
    Grace, David
    Mohammed, Abbas
    WCDMA Capacity and Coverage Enhancement from Multiple High Altitude Platform Configuration2007Conference paper (Refereed)
  • 5257. Hult, Tommy
    et al.
    Mohammed, Abbas
    A Combined Satellite Diversity and Compact MIMO Antenna Configurations for High Data Rate Communications2007Conference paper (Refereed)
  • 5258. Hult, Tommy
    et al.
    Mohammed, Abbas
    Active Signal Processing Algorithms for Controlling Electromagnetic Fields: a Tutorial2008Conference paper (Refereed)
  • 5259. Hult, Tommy
    et al.
    Mohammed, Abbas
    Active Suppression of Electromagnetic Fields2004Conference paper (Refereed)
  • 5260. Hult, Tommy
    et al.
    Mohammed, Abbas
    Application of Space-Time Signal Processing and Active Control Algorithms for the Suppression of Electromagnetic Fields2011In: Applied Signal and Image Processing: Multidisciplinary Advancements / [ed] Qahwaji, Rami; Green, Roger; Hines, Evor, Hershey: IGI Global , 2011, p. 45-60Chapter in book (Refereed)
    Abstract [en]

    Several studies have been conducted on the effects of radiation on the human body. This has been especially important in the case of radiation from hand held mobile phones. The amount of radiation emitted from most mobile phones is very small, but given the close proximity of the phone to the head it might be possible for the radiation to cause harm. The suggested approach involves the use of adaptive active control algorithms and a full space-time processing system setup (i.e. multiple antennas at both the transmitter and receiver side or MIMO), with the objective of reducing the possibly harmful electromagnetic radiation emitted by hand held mobile phones. Simulation results show the possibility of using the adaptive control algorithms and MIMO antenna system to attenuate the electromagnetic field power density.

  • 5261. Hult, Tommy
    et al.
    Mohammed, Abbas
    Assessment of a HAP Diversity System Employing Compact MIMO-Tetrahedron Antenna2007Conference paper (Other academic)
  • 5262. Hult, Tommy
    et al.
    Mohammed, Abbas
    Assessment of Multipath Propagation for a 2.4 GHz Short-Range Wireless Communication System2007Conference paper (Refereed)
    Abstract [en]

    In this paper we assess the multipath propagation effects of a short-range wireless device operating at 2.4 GHz in an indoor office environment. The investigations are carried out using FEM simulations and measurement trials for NLOS and LOS propagation scenarios. The FEM simulations will also be used for assessing the influence on propagation when doors are opened or closed. Finally, we investigate a single-input multiple-output (SIMO) antenna receive diversity system utilizing different combining techniques to improve the performance over a fading radio channel in a NLOS propagation environment. Simulation results show that a substantial diversity gain would be achieved by using this system. © 2007 IEEE

  • 5263. Hult, Tommy
    et al.
    Mohammed, Abbas
    CAPACITY OF A SATELLITE DIVERSITY SYSTEM EMPLOYING MULTIPLE POLARIZATIONS2006Conference paper (Refereed)
    Abstract [en]

    In this paper we address the potential gain of using compact MIMO antenna array configurations in conjunction with satellite diversity techniques in order to increase the data rates in satellite communication systems. Simulation results show that by exploiting the additional multiple polarization channels and satellite diversity we can achieve considerable capacity gain compared to the single satellite case.

  • 5264. Hult, Tommy
    et al.
    Mohammed, Abbas
    CAPACITY OF MULTIPLE HAP SYSTEM EMPLOYING MULTIPLE POLARIZATIONS2006Conference paper (Refereed)
    Abstract [en]

    In this paper we investigate the potential increase in capacity of HAP (High Altitude Platforms) communication systems using compact MIMO antenna array configurations in conjunction with HAP diversity techniques. In addition, we evaluate the system performance for different separation angles between HAPs. Simulation results show that the HAP diversity system provides superior performance compared to the single HAP case.

  • 5265. Hult, Tommy
    et al.
    Mohammed, Abbas
    COMBINED POLARIZATION AND SATELLITE DIVERSITY FOR HIGH DATA RATE COMMUNICATIONS2006Conference paper (Refereed)
    Abstract [en]

    This paper addresses the potential gain of using multiple-input multiple-output (MIMO) principle in order to increase the bandwidth efficiency in satellite communication systems. In particular, we consider the increase in channel capacity that is possible by exploiting satellite and polarization diversity. In addition, we investigate the effect of using different compact MIMO polarization antenna configurations and power control on the information theoretic capacity of the total transmission channel of the satellite system.

  • 5266. Hult, Tommy
    et al.
    Mohammed, Abbas
    Compact MIMO Antennas and HAP Diversity for Enhanced Data Rate Communications2007Conference paper (Refereed)
    Abstract [en]

    In this paper we address the potential gain of using various compact MIMO antenna array configurations in conjunction with HAP (High Altitude Platforms) diversity techniques in order to enhance the data rates in HAP communication systems. We will also investigate the effects of spatial correlation and mutual coupling between the separate antenna elements on system performance. Simulation results show that although the capacity is degraded by correlation and mutual coupling, we still achieve significant capacity gain compared to the single HAP case. Simulations also show the existence of an optimum separation angle between HAPs that maximizes capacity. © 2007 IEEE.

  • 5267. Hult, Tommy
    et al.
    Mohammed, Abbas
    Cooperative Beamforming for Wireless Sensor Networks2007Conference paper (Refereed)
  • 5268. Hult, Tommy
    et al.
    Mohammed, Abbas
    Estimation of the TOA performance of Loran-C2004Conference paper (Refereed)
    Abstract [en]

    Loran-C is a navigational aid that relies on the ability to make correct estimates of the Times of Arrival (TOAs) of signals received over a noisy radio channel. How good is the performance of Loran-C in this respect? Is it close to optimal? Are there perhaps better estimation techniques available than we currently employ? In this paper we use Estimation Theory to find the optimal limit of the accuracy of TOA estimates, for a given signal-to-noise ratio (SNR). Specifically, we compute the Cramer-Rao Lower Bound (CRLB) which specifies the absolute minimum error variance that can be achieved by an unbiased estimator. From the CRLB we can estimate the best repeatable accuracy that can be attained using a set of TOAs. We compute here the CRLBs for the TOA of a Loran-C signal with both Additive White Gaussian Noise (AWGN) and Additive Coloured Gaussian Noise (ACGN). We then employ the Maximum Likelihood Estimator (MLE) and compare its results with that of CRLB. Simulation results show that the MLE approaches the minimum variance obtained by CRLB for SNR values of practical and reliable Loran-C operation.

  • 5269. Hult, Tommy
    et al.
    Mohammed, Abbas
    HAP Diversity and Compact MIMO Antennas for High Data Rate Communications2006Conference paper (Refereed)
    Abstract [en]

    In this paper we address the potential gain of using compact MIMO antenna array configurations in conjunction with HAP diversity and OFDM techniques in order to increase the data rates in HAP communication systems. Simulation results show that the MIMO system provides superior performance as compared to the single HAP case.

  • 5270. Hult, Tommy
    et al.
    Mohammed, Abbas
    Indoor Propagation Simulation using FEM for Short-Range Wireless Communication Systems Operating at 2.4 GHz2005Conference paper (Refereed)
    Abstract [en]

    In this paper we investigate the wave propagation effects of a short-range wireless device, like the Bluetooth, in an indoor office environment. Specifically, we investigate line of sight (LOS) and non line of sight (NLOS) propagation scenarios and verify the theoretical statistics of the fading using real measurements and finite element method (FEM) simulations of the environment. The simulations are also used for assessing the impact on propagation when doors are opened or closed. In addition, we also investigate the improvement in performance resulting from receive diversity gain of a system employing multiple receive antennas with various combining techniques.

  • 5271. Hult, Tommy
    et al.
    Mohammed, Abbas
    MIMO ANTENNA APPLICATIONS FOR HIGH ALTITUDE PLATFORMS2006Conference paper (Refereed)
    Abstract [en]

    In this paper we address the potential gain of using compact MIMO antenna array configurations in conjunction with HAP (High Altitude Platforms) diversity techniques in order to increase the data rates in HAP communication systems. Simulation results show that the MIMO system provides superior performance as compared to the single HAP case.

  • 5272. Hult, Tommy
    et al.
    Mohammed, Abbas
    MIMO Antenna Applications for LEO Satellite Communications2005Conference paper (Refereed)
    Abstract [en]

    This paper addresses the potential gain of using multiple antennas and MIMO-OFDM techniques in order to increase the bandwidth efficiency in satellite communication systems. In particular, we consider the increase in channel capacity that is possible by exploiting satellite and polarization diversity. In addition, we investigate the effect of using different compact MIMO polarization antenna configurations and power control on the information theoretic capacity of the total transmission channel of the satellite system.

  • 5273. Hult, Tommy
    et al.
    Mohammed, Abbas
    MIMO applications for interference mitigation in multiple high altitude platform WCDMA systems2009Conference paper (Refereed)
    Abstract [en]

    In this paper we investigate the possibility of multiple HAP coverage of a common cell area. In particular we study the uplink system performance since it is considered as a worst case scenario. In order to obtain further enhancement (interference mitigation) we also apply space-time diversity techniques, such as Single-Input Multiple-Output (SIMO) receive diversity or Multiple-Input Multiple-Output (MIMO) diversity, to improve the spectrum reuse in the multiple HAP scenario. We will show the level of improvement using SIMO and MIMO algorithms, the practical limits on the number of HAPs and SIMO/MIMO system dimension in response to traffic demands and the type of service used.

  • 5274. Hult, Tommy
    et al.
    Mohammed, Abbas
    MIMO for HAPs: an idea whose time has come2006Conference paper (Refereed)
    Abstract [en]

    In this paper we address the potential gain of using compact MIMO antenna array configurations in conjunction with HAP diversity techniques in order to increase the data rates in HAP communication systems. Simulation results show that the MIMO system provides superior performance as compared to the single HAP case

  • 5275. Hult, Tommy
    et al.
    Mohammed, Abbas
    MULTIPATH PROPAGATION ASSESSMENT FOR A 2.4 GHZ SHORT-RANGE WIRELESS COMMUNICATION SYSTEM2006Conference paper (Refereed)
    Abstract [en]

    In this paper we assess the effects of multipath propagation on the link performance of a short-range wireless device, like the Bluetooth, in an indoor office environment. Specifically, we analyze the non line of sight (NLOS) propagation scenario and confirm the theoretical statistics of the fading using real measurements and finite element method (FEM) simulations of the environment. The simulations are also used for assessing the impact of multipath propagation when doors are opened or closed. In addition, we also investigate the improvement in performance resulting from receive diversity gain of a system employing multiple receive antennas with various combining techniques.

  • 5276. Hult, Tommy
    et al.
    Mohammed, Abbas
    Novel Applications of MIMO Antenna System for Active Suppression of Electromagnetic Fields2005Report (Other academic)
    Abstract [en]

    Active suppression of noise and vibrations is a well established field of research with many applications in acoustic and mechanical industries. In this report we test some of these active control methods combined with MIMO antenna system in order to assess their validity and performance when applied to electromagnetic fields. The application that we evaluated is a model of a mobile phone equipped with one ordinary transmitting antenna and a number of actuator-antennas which purpose is to cancel out the electromagnetic field at a specific volume in space (e.g. at the human head) while maintaining a predefined level of the overall output power of the system. This power control is achieved through the use of a quadratic constraint on the active control algorithm. In addition, we will also investigate the impact of MIMO antenna parameters and carrier frequency on the performance of the system. Simulation results show the promise of using the adaptive control algorithms and MIMO system to attenuate the electromagnetic field power density.

  • 5277. Hult, Tommy
    et al.
    Mohammed, Abbas
    Performance Evaluation of Adaptive Signal Processing and MIMO Antenna System for the Reduction of Electromagnetic Field Density2007Conference paper (Refereed)
  • 5278. Hult, Tommy
    et al.
    Mohammed, Abbas
    Power Constrained Active Suppression of Electromagnetic Fields Using MIMO Antenna System2004Conference paper (Refereed)
  • 5279. Hult, Tommy
    et al.
    Mohammed, Abbas
    Power Constrained Space-Time Processing for Suppression of Electromagnetic Fields2005In: Journal of Communication Software and Systems, ISSN 1845-6421, E-ISSN 1846-6079, Vol. 1, no 1Article in journal (Refereed)
    Abstract [en]

    Active suppression of noise and vibrations is a well established field of research with many applications in acoustic and mechanical industries. In this paper we investigate the possibility of applying these adaptive active control methods with the aim of lowering the electromagnetic power density at a specific volume in space using the superposition principle and space-time processing employing the full MIMO (Multiple Input Multiple Output) antenna system setup. The application that we evaluated is a model of a mobile phone equipped with one ordinary transmitting antenna and two actuator-antennas which purpose is to cancel out the electromagnetic field at the human head while maintaining a predefined level of the overall output power of the system. This power control is achieved through the use of a quadratic constraint on the active control algorithm. Simulation results show the promise of using the adaptive control algorithms and MIMO system to attenuate the electromagnetic field power density

  • 5280. Hult, Tommy
    et al.
    Mohammed, Abbas
    Suppression of EM Fields using Active Control Algorithms2004In: Radioengineering, ISSN 1210-2512, E-ISSN 1805-9600, Vol. 13, no 3, p. 22-25Article in journal (Refereed)
    Abstract [en]

    Active methods for attenuating acoustic pressure fields have been successfully used in many applications. In this paper we investigate some of these active control methods in combination with a MIMO antenna system in order to assess their validity and performance when applied to electromagnetic fields. The application that we evaluated in this paper is a model of a mobile phone equipped with one ordinary transmitting antenna and two actuator-antennas which purpose is to reduce the electromagnetic field at a specific area in space (e.g. at the human head). Simulation results show the promise of using the adaptive active control algorithms and MIMO system to attenuate the electromagnetic field power density.

  • 5281. Hult, Tommy
    et al.
    Mohammed, Abbas
    The Effect of Mutual Coupling on a High Altitude Platform Diversity System Using Compact Antenna Arrays2010In: International Journal of Antennas and Propagation, ISSN 1687-5869, E-ISSN 1687-5877, Vol. 2010Article in journal (Refereed)
    Abstract [en]

    We analyze the destructive effects of mutual coupling and spatial correlation between the separate antenna elements on a combined diversity system consisting of multiple HAPs (High-Altitude Platforms) employing various compact MIMO (Multiple-Input Multiple-Output) antenna array configurations, in order to enhance the mutual information in HAP communication links. In addition, we assess the influence of the separation angle between HAPs on system performance, and determine the optimal separation angles that maximize the total mutual information of the system for various compact MIMO antennas. Simulation results show that although the mutual information is degraded by mutual coupling and spatial correlation, the proposed HAP diversity system still provides better performance compared to a nondiversity system for all tested scenarios.

  • 5282. Hult, Tommy
    et al.
    Mohammed, Abbas
    THE IMPACT OF MIMO ANTENNA SYSTEM AND CARRIER FREQUENCYON ACTIVE CONTROL SUPPRESSION OF ELECTROMAGNETIC FIELD2004Conference paper (Refereed)
    Abstract [en]

    There have been several studies done, with conflicting results, on the effects of cell-phone radiation on the human body. The amount of radiation emitted from most cell phones is very minute. However, given the close proximity of the phone to the head, it is entirely possible for the radiation to cause harm. If you want to be on the safe side, the easiest way to minimize the radiation you are exposed to is to position the antenna as far from your head as possible. Utilizing a hands-free kit, a car-kit antenna or a cell phone whose antenna is even a couple of inches farther from the head can do this most effectively. This paper makes a contribution to that discussion by proposing a new approach by employing adaptive active control algorithms combined with a Multiple-Input Multiple-Output (MIMO) antenna system to suppress the electromagnetic field at a certain area in space. We will also investigate the effects of the size and number of MIMO antenna elements and test the algorithms at different carrier frequencies (e.g., other GSM bands and UMTS).

  • 5283. Hult, Tommy
    et al.
    Mohammed, Abbas
    Theoretical Analysis and Assessment of Depolarization Effects on the Performance of High Altitude Platforms2008Conference paper (Refereed)
  • 5284. Hult, Tommy
    et al.
    Mohammed, Abbas
    Falletti, Emanuela
    Sellone, Fabrizio
    Analysis of Depolarizing Effects and Impact on the Performance of a Multiple Satellite System Employing Polarization Diversity2007Conference paper (Refereed)
  • 5285. Hult, Tommy
    et al.
    Mohammed, Abbas
    Falletti, Emanuela
    Sellone, Fabrizio
    Multi-Antenna Multi-HAP Channel Model for Space-Polarization2008Conference paper (Refereed)
  • 5286. Hult, Tommy
    et al.
    Mohammed, Abbas
    Grace, David
    WCDMA Coverage Enhancement from Multiple High Altitude Platforms2008Conference paper (Refereed)
  • 5287. Hult, Tommy
    et al.
    Mohammed, Abbas
    Grace, David
    Yang, Zhe
    Performance of a Multiple HAP System Employing Multiple Polarization2006Conference paper (Refereed)
  • 5288. Hult, Tommy
    et al.
    Mohammed, Abbas
    Nordebo, Sven
    Active Suppression of Electromagnetic Fields Using a MIMO Antenna System2003Conference paper (Refereed)
    Abstract [en]

    Active suppression of noise and vibrations is a well established field of research with many applications in acoustic and mechanical industries. In this paper we test some of these active control methods in order to assess their validity and performance when applied to electromagnetic fields. The application that we evaluated is a model of a mobile telephone equipped with one ordinary transmitting antenna and two actuator-antennas which purpose is to cancel out the electromagnetic field at a specific point in space (e.g. at your head).

  • 5289. Hult, Tommy
    et al.
    Mohammed, Abbas
    Yang, Zhe
    Grace, David
    Performance of a multiple HAP system employing multiple polarization2010In: Wireless Personal Communications, Springer , 2010, Vol. 52, no 1, p. 105-117Conference paper (Refereed)
    Abstract [en]

    In this paper we address the potential gain of using compact MIMO antenna array configurations in conjunction with HAP (High Altitude Platforms) diversity techniques in order to increase the data rates in HAP communication systems. We will also investigate the effects of spatial correlation and mutual coupling between the separate antenna elements on system performance. Simulation results show that although the capacity is degraded by correlation and mutual coupling, we still achieve significant capacity gain compared to the single HAP case. In addition, we evaluate the performance of the system for different separation angles between HAPs, and determine the optimal separation angle that maximizes the total capacity of the system. © 2008 Springer Science+Business Media, LLC.

  • 5290.
    Hultberg, Jenny
    et al.
    Blekinge Institute of Technology, School of Management.
    Klarenius, Karna
    Blekinge Institute of Technology, School of Management.
    Liljekvist, Per
    Blekinge Institute of Technology, School of Management.
    Arbetstidsförkortning: för ökad arbetstillfredsställelse och bättre relationer.2004Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [en]

    Background: Already in the 16th century Owen discussed that it was not a good idea to have children working long working hours in three shifts. This approach was introduced at his factory, but was also given a lot of criticism. First in 1962 the idea of 6-hours working day was awakened in Sweden. Since then there has been a number of attempts, among them at the city of Helsingborg´s and Höganäs´ elder care as well at Toyota Center in Mölndal. Problem: Today’s companies are focused on traditional measurements, for example profitability and productivity, even when it comes to shorter working hours. On the other hand, there is not much investigated regarding the so called inner values, such as work satisfaction and relations. We have not found any study that deals with the result of shortened working hours and how it has effected work satisfaction and relation in an organization. Purpose: By studying the psychological abilities; work environment and motivation as well as the sociological abilities; leadership, group and conflict in two companies, we intended to see if there had been any changes in the inner values; work satisfaction and relations through shortened working hours. Method: The study has started out from a qualitative method in which phone interviews have been used for collecting data. The interviews have been carried out at AWJ-Tryck AB and Stora Enso Kvarnsveden AB. We have chosen to study the inner values from the employee’s point of view, but to get a picture of how the change has affected the employees we have chosen to interview supervisors and people from the board as well. Conclusions: The employee’s experiences with shorter working hours is that they are more motivated, which also have led to an increased work satisfaction. Besides that the social part of the work environment works better today. When these factors work in a company the employees feel more motivated which makes them perform better. The answer to our research question is that the employee’s inner values; work satisfaction and relations, shows a positive result in collaboration with shorter work hours.

  • 5291.
    Hultgren, Anders
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Electrical Engineering.
    Bui, S.
    Linnér, Jörgen
    Ranstad, Per
    Lenells, Matz
    Fault tolerant high voltage resonant power converter application2013Conference paper (Refereed)
    Abstract [en]

    A high voltage and high power fault tolerant application of a resonant converter is presented. The resonant converter load shows frequent short circuits making the load voltage drop to zero within some us, implying high stress on the main circuit components. A load voltage short circuit fault tolerant system is suggested by including a novel way of augmenting the controller with a load voltage estimator. The estimator can detect load voltage short circuit and will then be a part of a fault tolerant high voltage resonant converter.

  • 5292.
    Hultgren, Anders
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Electrical Engineering.
    Kulesza, Wlodek
    Blekinge Institute of Technology, School of Engineering, Department of Electrical Engineering.
    Nilsson, Magnus
    Walther, Björn
    Integration av matematik och teknik på ingenjörsutbildningar2009Conference paper (Refereed)
    Abstract [en]

    An possible integration of mathematics and applications within engineering is presented. The integration method has been used at The university of Kalmar. The method is described and experiences are presented.

  • 5293.
    Hultgren, Anders
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Electrical Engineering.
    Melin, Jan
    Ranstad, Per
    Asymmetric Limit Cycles in an Industrially Applied Controlled Resonant Converter2009Conference paper (Refereed)
    Abstract [en]

    An industrially applied LCC power converter is modelled as a hybrid system. It is found that the hybrid system given a parameter set up and different initial conditions has three different limit cycles, one unstable and two asymmetric stable limit cycles. Effects of the asymmetric limit cycles are considered.

  • 5294. Hultgren, Anders
    et al.
    Melin, Jan
    Ranstad, Per
    Limit cycle control of an industrially applied resonant converter modelled as a hybrid system2011Conference paper (Refereed)
    Abstract [en]

    Limit cycle control of an industrially applied high power, high voltage resonant power converter is modelled as a hybrid system. It is found that the hybrid system with three continuous states and one logic state given a parameter set up and different initial conditions has a rich solution set indicating possible problems in the industrial application. The solution set are one central closed trajectory and two asymmetric types of limit cycles.

  • 5295. Hultgren, Anders
    et al.
    Melin, Jan
    Ranstad, Per
    Limit Cycles in an Industrially Applied Hybrid System2010Conference paper (Refereed)
    Abstract [en]

    An industrially applied LCC power converter is modelled as a hybrid system. It is found that the hybrid system with three continuous states and one logic state given a parameter set up and different initial conditions has among other solutions one central closed trajectory and two types of limit cycles, on the left and the right side. The other solutions are indicated.

  • 5296. Hultgren, Anders
    et al.
    Nilsson, Magnus
    Kulesza, Wlodek
    Walther, Björn
    Integration av matematik och teknik på ingenjörsutbildningar2008Conference paper (Other academic)
    Abstract [sv]

    I detta bidrag presenterar vi en uppläggning av integrerade kurser i matematik och tillämpningar, vilken använts inom högskoleingenjörsutbildningen vid Högskolan i Kalmar. Kursverksamheten, som bedrivs inom ramen för kurspaketet ingenjörsvetenskap, tillgodoser såväl behovet av att betona matematikens roll som ett generellt och abstrakt verktyg för problemlösning som behovet av att ge studenterna bra baskunskaper i matematik i anslutning till möjliga tillämpningsområden.

  • 5297.
    Hultgren, Annika
    et al.
    Blekinge Institute of Technology, School of Health Science.
    Johansson, Eva
    Blekinge Institute of Technology, School of Health Science.
    Patienters upplevelser ur ett livsvärldsperspektiv efter genomgången kranskärlsoperation: Litteraturstudie2009Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    Kranskärlsoperationer är idag ett vanligt förekommande kirurgiskt ingrepp. Årligen opereras 4200 personer i Sverige. Studier har visat att patienters upplevelser efter en genomgången kranskärlsoperation många gånger är komplicerade, med ökade behov av support och besvär såsom minnesstörningar, nedstämdhet och fysiska besvär. Syftet med studien var att belysa patienters upplevelser ur ett livsvärldsperspektiv efter genomgången kranskärlsoperation. Upplevelserna speglade tiden på sjukhuset och upplevelser i hemmet efter operationen. Metoden var en systematisk litteraturstudie som inbegrep åtta artiklar med kvalitativ analysmetod. Artiklarna bestod av intervjuer gjorda med patienter upp till sju år efter genomgången kranskärlsoperation, och analysen genomfördes utifrån Graneheim & Lundmans beskrivning av kvalitativ innehållsanalys. Resultatet mynnade ut i tre kategorier: upplevelser av fysiska förändringar, patienters känslor och tankeupplevelser samt betydelsen av socialt nätverk. Många av patienterna beskrev oväntade komplikationer som nedsatt koncentrationsförmåga, minnesförlust och att det tog lång tid att återfå en normal fysisk förmåga igen. Flera upplevde återgången till det normala som en lång process, ”transition” där det krävdes både fysisk som psykisk uthållighet. Några patienter tyckte att operationen hade uppfyllt mer än vad de förväntat sig, medan andra hade väntat sig mer. Vikten av socialt stöd och uppmuntran beskrevs som en viktig del för att kunna uppnå ett bra resultat i rehabiliteringen. Studien visade på hur patientens livsvärld påverkades efter en kranskärlsoperation och betydelsen av utökad information till de patienter som upplevde oro, ängslan eller var instabila fysiskt eller psykiskt, vilket kunde vara ett sätt att underlätta återgången till vardagen efter operationen. Slutsatsen blev att man bör utöka informationen till patienterna så de blir mer förberedda inför återhämtningen.

  • 5298.
    Hultgren, Per
    Blekinge Institute of Technology, School of Management.
    The Motivating Suggestion System2008Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    This case study investigates the suggestion system of a manufacturing plant with the purpose of getting insight about how a suggestion system should be designed to support the continuous improvement discipline Kaizen in the best way possible. The cooperating company has recently introduced Kaizen to the organization as part of a transaction toward lean production. The study was conducted using semi-structured interviews along with observations. The problem was approached from a motivational perspective, and a motivational framework has been created for this situation by combining research from the four motivation theories; Attribution theory, Social cognitive theory, Self-determination theory and Expectancy theory. The result from the study shows positive as well as negative aspects of the suggestion system at the factory that should be considered when designing a suggestion system that enhance the effect of Kaizen.

  • 5299.
    Hultgren, Richard
    et al.
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    Kullgard, Peter
    Blekinge Institute of Technology, Department of Software Engineering and Computer Science.
    Improving configuration management, quality management and development methods in the computer game industry2001Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    There is a lack of maturity in the software game development that results in development companies using their own invented, but not fully completed, procedures. Through a case study this master thesis gives an overview of the game developers maturity in configuration management, quality assurance and development methods in general. It also presents a suggestion on how to address the issues found in the case study.

  • 5300.
    Hultin, Daniel
    et al.
    Blekinge Institute of Technology, School of Management.
    Boström, Henrik
    Blekinge Institute of Technology, School of Management.
    Holmqvist, Jonas
    Blekinge Institute of Technology, School of Management.
    Ett företags kommunikationsstrategi – hur påverkas ledningens externa och interna kommunikationsstrategier vid en börsintroduktion?2008Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    Syfte: Syftet med denna uppsats är att studera hur en börsintroduktion påverkar ledningens kommunikationsstrategi i ett företag. Metod: Hela studien utfördes på företaget Waterjet i Ronneby med hjälp av kvalitativa intervjuer med anställda på ledande positioner i organisationen. Slutsatser: Både internt och externt ser vi skillnader jämfört med hur det var före introduktionen. Den största förändringen är i den externa kommunikationen, där företaget nu måste hantera fler ägare, analytiker och investerare. Internt har ledningen utformat nya riktlinjer och policys för hur kommunikationen ska hanteras på bästa vis. Som en del av den interna kommunikationsstrategin har formella möten fått mer betydelse än tidigare, då anställda får diskutera vad börsintroduktionen innebär för deras arbete. Avsikten är att kommunikationen mellan mellanchefer och anställda ska fungera samt att den blir viktigare i samband med att företaget blir publikt, då ryktesspridningar om företaget ska undvikas externt.

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