| 1. |
- Bollen, Math, et al.
(författare)
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Limits for voltage distortion in the frequency range 2 to 9 kHz
- 2008
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Ingår i: I E E E Transactions on Power Delivery. - I E E E. - 0885-8977. ; 23:3
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Tidskriftsartikel (övrigt vetenskapligt)abstract
- This paper addresses voltage distortion in the frequency range 2 to 9 kHz, above what is normally considered in harmonic studies. By extrapolating the voltage-distortion limits that exist in international standards for distortion up to 2 kHz, it is concluded that 0.5% of nominal voltage per 200-Hz band is a safe limit. This limit is next used to estimate the number of small generator units (1-10 kW) that can be connected to a low-voltage grid. It is concluded that in some cases the connection of one or just a few units already leads to a distortion level above the limit.
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| 2. |
- Gil-de-Castro, A., et al.
(författare)
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LED street lighting a power quality comparison among street light technologies
- 2013
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Ingår i: Lighting Research and Technology. - Sage Science Press (UK). - 1477-1535.
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Tidskriftsartikel (övrigt vetenskapligt)abstract
- High-pressure sodium lamps are currently the main lamps used in public lighting. However, the possibility of using high-power light emitting diode (LEDs) for street lighting is growing continuously due to their greater energy efficiency, robustness, long life and light control. The aim of this paper is to study the power quality of high-power lighting networks based on LED and high-pressure sodium lamps. Both electromagnetic and dimmable electronic ballasts, which can dim the lamp output smoothly and uniformly, have been used connected to high-pressure sodium lamps. High-pressure sodium lamps connected to electronic equipment have been tested with different arc power levels using dimming on a 230 V power supply. The study presented in this paper is completely based on measurements, including harmonic currents in the frequency range up to 150 kHz for all the technologies. The main results show a broadband spectrum in LED lamps which confirms other research in fluorescent lamps powered by high-frequency ballasts. Results also indicate a decrease in the harmonic value with increasing harmonic order, and a decrease in the harmonic value at half load (60%) compared with full load (100%). Although total harmonic distortion of the current is lower with high-pressure sodium lamps connected to electronic rather than electromagnetic ballasts, LED lamps achieved the lowest total harmonic distortion of curren
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| 3. |
- Lundmark, Martin, et al.
(författare)
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Required changes in emission standards for high-frequency noise in power systems
- 2006
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Ingår i: International Journal of Energy Technology and Policy. - Inderscience Publishers. - 1472-8923. ; 4:1-2
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Tidskriftsartikel (övrigt vetenskapligt)abstract
- This paper discusses some recent developments that make the existing standards on the emission of high-frequency noise in power systems need to be reconsidered. It is shown that it is possible for an equipment to remain below the emission limits while at the same time the disturbance level increases beyond what was intended by the standard document. Further, the change from analog to digital communication and the use of communication via the power system, make that the permitted disturbance levels need to be reconsidered. This paper also contains an example of measured high-frequency noise and proposes a framework for re-coordination of emission and immunity levels.
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| 4. |
- Olofsson, Peter, et al.
(författare)
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Genetic links between the acute-phase response and arthritis development in rats.
- 2002
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Ingår i: Arthritis Rheum. - American College of Rheumatology. - 0004-3591. ; 46:1, s. 259-268
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The acute-phase inflammatory response is closely correlated with the development of rheumatoid arthritis, but the pathophysiologic role of its specific components is largely unknown. We investigated the genetic control of the acute-phase protein response in pristane-induced arthritis (PIA), which is a chronic erosive arthritis model in rats. METHODS: Plasma levels of the acute-phase proteins interleukin-6 (IL-6), alpha1-acid glycoprotein (orosomucoid), fibrinogen, and alpha1-inhibitor3 were quantified in 3 strains of rats during the development and progression of disease: DA and LEW.1F, which are susceptible to arthritis, and E3, which is resistant. Genetic linkage analysis was performed on an F2 intercross between E3 and DA to determine the genetic control of the acute-phase response in arthritis. Elevated levels of alpha1-acid glycoprotein were associated with acute inflammation, whereas levels of IL-6 were increased during the entire course of the disease. RESULTS: Using these acute-phase markers as quantitative traits in linkage analysis revealed a colocalization of loci controlling the acute-phase response and regions previously shown to control the development of arthritis in chromosomes 10, 12, and 14. In addition, 2 loci that were not associated with arthritis were found to regulate serum levels of the acute-phase protein Apr1 (acute-phase response 1) at the telomeric end of chromosome 12 and Apr2 on chromosome 5. CONCLUSION: The PIA model in rats is a useful tool for understanding some of the pathways leading to chronic erosive arthritis. The analysis of acute-phase proteins in PIA and its application as quantitative traits for studying the genetics of arthritis will promote the understanding of the genetic regulation of the acute-phase response.
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| 5. |
- Lindholm, Åsa, et al.
(författare)
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Effect of sibutramine on weight reduction in women with polycystic ovary syndrome : a randomized, double-blind, placebo-controlled trial
- 2008
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Ingår i: Fertility and Sterility. - 0015-0282. ; 89:5, s. 1221-1228
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To examine the efficacy of sibutramine together with brief lifestyle modification for weight reduction in obese women with polycystic ovary syndrome (PCOS). DESIGN: Investigator-initiated, multicenter, double-blind, randomized, parallel-group clinical trial. SETTING: Departments of Obstetrics and Gynecology in primary care, referral centers, and private practice. PATIENT(S): Forty-two patients with confirmed PCOS were included in the study, and 34 patients completed the study. INTERVENTION: Sibutramine 15 mg once daily together with brief lifestyle modification was compare with placebo together with brief lifestyle modification. MAIN OUTCOME MEASURE(S): The primary endpoint was to assess weight loss. Secondary endpoints included the efficacy of sibutramine for treatment of menstrual pattern and cardiovascular risk factors. RESULT(S): After 6 months the sibutramine group had lost 7.8 +/- 5.1 kg compared with a weight loss of 2.8 +/- 6.2 kg in the placebo group. Sibutramine treatment resulted in significant decreases in apolipoprotein B, apolipoprotein B/apolipoprotein A ratio, triglycerides, and cystatin C levels. CONCLUSION(S): Sibutramine in combination with lifestyle intervention results in significant weight reduction in obese patients with PCOS. In addition to the weight loss, sibutramine seems to have beneficial effects on metabolic and cardiovascular risk factors.
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| 6. |
- Sundelöf, Johan, et al.
(författare)
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Cystatin C Levels are Positively Correlated with both Aβ42 and Tau Levels in Cerebrospinal Fluid in Persons with Alzheimer's Disease, Mild Cognitive Impairment, and Healthy Controls
- 2010
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Ingår i: Journal of Alzheimer's Disease. - 1387-2877. ; 21:2, s. 471-478
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Tidskriftsartikel (refereegranskat)abstract
- Cystatin C is suggested to be involved in neurodegeneration and the development of Alzheimer's disease (AD) by binding to soluble amyloid-beta (Abeta) peptides. Studies of cystatin C levels in cerebrospinal fluid (CSF) in relation to risk of AD are conflicting and relations between cystatin C, Abeta42, and tau levels in CSF in AD, mild cognitive impairment (MCI), and healthy controls are unknown. The objective of this study was to investigate cystatin C, Abeta42, and tau levels in CSF in AD, MCI, and controls. As a secondary aim, the relationships between cystatin C, Abeta42, and tau levels across disease groups were investigated. Cystatin C, Abeta42, total tau, and phosphorylated tau levels in CSF were analyzed by turbidimetry (cystatin C) and xMAP Luminex technology (Abeta and tau) in persons with AD (n=101), MCI (n=84), and healthy control subjects (n=28). Mean cystatin C levels were similar in cases of AD (5.6 mumol/L +/- 1.7), MCI (5.4 mumol/L +/- 1.48), and controls (5.6 mumol/L +/- 1.6). However, CSF cystatin C levels were strongly and positively correlated with total tau and phosphorylated tau levels (r=0.61-0.81, p< 0.0001) and Abeta42 (r=0.35-0.65, p< 0.001) independent of age, gender, and APOE genotype. Mean CSF cystatin C levels did not differ between patients with AD and MCI and healthy controls. Interestingly, cystatin C levels were positively correlated with both tau and Abeta42 levels in CSF independent of age, gender, and APOE genotype.
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| 7. |
- Sundelöf, Johan, et al.
(författare)
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Higher Cathepsin B Levels in Plasma in Alzheimer's Disease Compared to Healthy Controls
- 2010
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Ingår i: Journal of Alzheimer's Disease. - 1387-2877. ; 22:4, s. 1223-1230
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Tidskriftsartikel (refereegranskat)abstract
- Cathepsin B is suggested to be involved in amyloid-β (Aβ) processing and Alzheimer's disease (AD). Studies of cathepsin B levels in plasma and cerebrospinal fluid (CSF) have not been previously performed. We examined cathepsin B levels in plasma and CSF samples in persons with AD, mild cognitive impairment (MCI), and healthy controls in order to test the hypothesis that cathepsin B levels can discriminate persons with AD or MCI from healthy controls. Cathepsin B, Cystatin C, Aβ1-40 and Aβ1-42, total tau, phosphorylated tau, and albumin levels in plasma and CSF were analyzed by ELISA (Cathepsin B) turbidimetry (cystatin C), xMAP Luminex technology (Aβ1-40 and Aβ1-42 and tau), and Cobas C501 analyzer (albumin) in persons with AD (n=101), MCI (n=84), and healthy control subjects (n=28). Plasma cathepsin B levels were higher in persons with AD compared to healthy controls, both in unadjusted models and in multivariable models adjusting for age, gender, APOE genotype, cystatin C, and albumin levels: Odds ratio (OR) for AD per 1 SD of plasma cathepsin B; 2.04, 95% confidence interval (CI); 1.01-4.14, p= 0.05. There was no difference between diagnostic groups in cathepsin B levels in CSF: OR for AD per 1 SD of CSF cathepsin B; 0.93, 95% CI; 0.37-2.30, p= 0.87. Plasma cathepsin B levels were higher in persons with AD compared to healthy controls whereas there was no difference between diagnostic groups in cathepsin B levels in CSF. Further investigation of cathepsin B as a predictor of AD is warranted.
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| 8. |
- Appelgren, Patrik, et al.
(författare)
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Experimental Study of Electromagnetic Effects on Solid Copper Jets
- 2010
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Ingår i: Journal of applied mechanics. - 0021-8936. ; 77:1, s. 011010
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we present a study of the interaction between all electric current pulse and a solid copper jet. Experiments were performed using a dedicated pulsed power supply delivering a current pulse of such amplitude, rise little, and duration that the jet is efficiently affected. The copper jet was created by using a shaped charge warhead. All electrode configuration consisting of two aluminum plates with a separation distance of 150 mm was used. The discharge current pulse and the voltages at the capacitors and at the electrodes were measured to obtain data oil energy deposition in and the resistance of the jet and electrode contact region. X-ray diagnostics were used to radiograph the jet, and by analyzing the radiograph, the degree of disruption of the electrified jet could be obtained. It was found that a current pulse with an amplitude of 200-250 kA and a rise time of 16 mu s could strongly enhance the natural fragmentation of the jet. In this case, the initial electric energy was 100 kJ and about 90% of the electric energy was deposited in the jet and electrodes. At the exit of the electrode region, the jet fragments formed rings with a radial velocity of up to 200 m/s, depending oil the initial electric energy in the pulsed power supply. [DOI: 10.1115/1.3172251]
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| 9. |
- Appelgren, Patrik, et al.
(författare)
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Modeling of a small helical magnetic flux compression generator
- 2008
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Ingår i: IEEE Transactions on Plasma Science. - 0093-3813. ; 36:5, s. 2662-2672
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Tidskriftsartikel (refereegranskat)abstract
- In order to gain experience in explosive pulsed power and to provide experimental data as the basis for computer modeling, a small high-explosive-driven helical magnetic flux-compression generator (FCG) was designed at the Swedish Defence Research Agency. The generator, of which three have been built, has an overall length of 300 mm and a diameter of 70 mm. It could serve as the energy source in a pulse-forming network to generate high-power pulses for various loads. This paper presents a simulation model of this helical FCG. The model, which was implemented in Matlab-Simulink, uses analytical expressions for the generator inductance. The model of resistive losses takes into account the heating of the conductors and the diffusion of the magnetic field into the conductors. The simulation results are compared with experimental data from two experiments with identical generators but with different seed currents, influencing the resistive losses. The model is used to analyze the performance of the generator.
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| 10. |
- Appelgren, Patrik, et al.
(författare)
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Small Helical Magnetic Flux-Compression Generators : Experiments and Analysis
- 2008
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Ingår i: IEEE Transactions on Plasma Science. - 0093-3813. ; 36:5, s. 2673-2683
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Tidskriftsartikel (refereegranskat)abstract
- In order to gain experience in explosive pulsed power and to provide experimental data for modeling, a small high-explosive-driven helical magnetic flux-compression generator (FCG) was designed at the Swedish Defence Research Agency (FOI). The generator, of which three have been built, has an overall length of 300 mm and a diameter of 70 mm. It could serve as the energy source in a pulse-forming network to generate high power pulses for various loads. This paper presents the design of, and tests with, this helical FCG. The generator had an initial inductance of 23 mu H and was operated into a load of 0.2 mu H. The generator is charged with 0.27 kg of high explosives (PBXN-5). Various types of diagnostics were used to monitor the operation of the generator, including current probes, optical fibers, and piezo gauges. With seed currents of 5.7 and 11.2 kA, final currents of 269 and 436 kA were obtained, corresponding to current amplification factors of 47 and 39. The peak of the current was reached about 30 mu s after the time of crowbar. The two generators showed only small losses in terms of 2 pi-clocking. Using signals from optical fibers, the deflection angle of the armature could be determined to be 10 degrees in good agreement with hydrodynamic simulations of the detonation process and the detonation velocity to be 8.7 km/s in agreement with tabulated value.
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