TY  - JOUR
AU  - Lazarević, Đorđe R.
AU  - Obrenović, Marija D.
AU  - Fetahović, Irfan S.
AU  - Osmokrović, Predrag V.
PY  - 2014
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/402
AB  - This paper discusses the possibility of applying the F-test and double t-test in problems related to the identification of number of radioactive isotopes in a contaminated area by using only counters for radiation detection. The descriptions of the F-test and the double t-test are given along with the corresponding tabular values that enable their implementation. Finally, the experiment is presented via two radioactive samples. The results of the experiment were treated in the manner proposed in the paper and satisfactory results were obtained.
T2  - Nuclear technology and radiation protection
T1  - Comparison of the Empirical Variances and Mean Values of Normally Distributed Populations of Nuclear Counts
VL  - 29
IS  - 4
SP  - 285
EP  - 288
DO  - 10.2298/NTRP1404285L
ER  - 

@article{
author = "Lazarević, Đorđe R. and Obrenović, Marija D. and Fetahović, Irfan S. and Osmokrović, Predrag V.",
year = "2014",
abstract = "This paper discusses the possibility of applying the F-test and double t-test in problems related to the identification of number of radioactive isotopes in a contaminated area by using only counters for radiation detection. The descriptions of the F-test and the double t-test are given along with the corresponding tabular values that enable their implementation. Finally, the experiment is presented via two radioactive samples. The results of the experiment were treated in the manner proposed in the paper and satisfactory results were obtained.",
journal = "Nuclear technology and radiation protection",
title = "Comparison of the Empirical Variances and Mean Values of Normally Distributed Populations of Nuclear Counts",
volume = "29",
number = "4",
pages = "285-288",
doi = "10.2298/NTRP1404285L"
}

Lazarević, Đ. R., Obrenović, M. D., Fetahović, I. S.,& Osmokrović, P. V.. (2014). Comparison of the Empirical Variances and Mean Values of Normally Distributed Populations of Nuclear Counts. in Nuclear technology and radiation protection, 29(4), 285-288.
https://doi.org/10.2298/NTRP1404285L

Lazarević ĐR, Obrenović MD, Fetahović IS, Osmokrović PV. Comparison of the Empirical Variances and Mean Values of Normally Distributed Populations of Nuclear Counts. in Nuclear technology and radiation protection. 2014;29(4):285-288.
doi:10.2298/NTRP1404285L .

Lazarević, Đorđe R., Obrenović, Marija D., Fetahović, Irfan S., Osmokrović, Predrag V., "Comparison of the Empirical Variances and Mean Values of Normally Distributed Populations of Nuclear Counts" in Nuclear technology and radiation protection, 29, no. 4 (2014):285-288,
https://doi.org/10.2298/NTRP1404285L . .

TY  - JOUR
AU  - Osmokrović, Predrag V.
AU  - Lončar, Boris B.
AU  - Stanković, Srboljub
PY  - 2006
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2980
AB  - This paper presents an innovative method for an efficient characterization of relevant characteristics of nonlinear overvoltage protection elements in low-voltage applications. Standard measuring equipment was modified to enable an efficient and repeatable experimental procedure in order to investigate characteristics of overvoltage diodes and varistors, in particular volt-ampere characteristic, volt-ohm characteristic, coefficient of nonlinearity, and dissipating energy. Furthermore, the pseudoempiric method using the area law has been developed to determine a pulse characteristic of a gas-filled surge arresters (GFSA). An innovative aging estimate algorithm was additionally used. The justification of the suggested method on commercial nonlinear overvoltage components was checked. Its protective characteristics were examined by both the classical approach and the new suggested method. The obtained results from both methods showed minimal discrepancies.
T2  - IEEE Transactions on Instrumentation and Measurement
T1  - The new method of determining characteristics of elements for overvoltage protection of low-voltage system
VL  - 55
IS  - 1
SP  - 257
EP  - 265
DO  - 10.1109/TIM.2005.862023
ER  - 

@article{
author = "Osmokrović, Predrag V. and Lončar, Boris B. and Stanković, Srboljub",
year = "2006",
abstract = "This paper presents an innovative method for an efficient characterization of relevant characteristics of nonlinear overvoltage protection elements in low-voltage applications. Standard measuring equipment was modified to enable an efficient and repeatable experimental procedure in order to investigate characteristics of overvoltage diodes and varistors, in particular volt-ampere characteristic, volt-ohm characteristic, coefficient of nonlinearity, and dissipating energy. Furthermore, the pseudoempiric method using the area law has been developed to determine a pulse characteristic of a gas-filled surge arresters (GFSA). An innovative aging estimate algorithm was additionally used. The justification of the suggested method on commercial nonlinear overvoltage components was checked. Its protective characteristics were examined by both the classical approach and the new suggested method. The obtained results from both methods showed minimal discrepancies.",
journal = "IEEE Transactions on Instrumentation and Measurement",
title = "The new method of determining characteristics of elements for overvoltage protection of low-voltage system",
volume = "55",
number = "1",
pages = "257-265",
doi = "10.1109/TIM.2005.862023"
}

Osmokrović, P. V., Lončar, B. B.,& Stanković, S.. (2006). The new method of determining characteristics of elements for overvoltage protection of low-voltage system. in IEEE Transactions on Instrumentation and Measurement, 55(1), 257-265.
https://doi.org/10.1109/TIM.2005.862023

Osmokrović PV, Lončar BB, Stanković S. The new method of determining characteristics of elements for overvoltage protection of low-voltage system. in IEEE Transactions on Instrumentation and Measurement. 2006;55(1):257-265.
doi:10.1109/TIM.2005.862023 .

Osmokrović, Predrag V., Lončar, Boris B., Stanković, Srboljub, "The new method of determining characteristics of elements for overvoltage protection of low-voltage system" in IEEE Transactions on Instrumentation and Measurement, 55, no. 1 (2006):257-265,
https://doi.org/10.1109/TIM.2005.862023 . .

TY  - JOUR
AU  - Lončar, Boris B.
AU  - Osmokrović, Predrag V.
AU  - Stanković, Srboljub
PY  - 2003
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2677
AB  - The goal of this paper is to determine use of gas filled surge arresters (GFSA) with a built-in radioactive sources in radiative environment. Furthermore, a pseudoempiric method has been developed to determine the GFSA pulse shape characteristics. These results are considered relevant for the use of this component in both military applications and space technology.
T2  - IEEE Transactions on Nuclear Science
T1  - Radioactive reliability of gas filled surge arresters
VL  - 50
IS  - 5
SP  - 1725
EP  - 1731
DO  - 10.1109/TNS.2003.818269
ER  - 

@article{
author = "Lončar, Boris B. and Osmokrović, Predrag V. and Stanković, Srboljub",
year = "2003",
abstract = "The goal of this paper is to determine use of gas filled surge arresters (GFSA) with a built-in radioactive sources in radiative environment. Furthermore, a pseudoempiric method has been developed to determine the GFSA pulse shape characteristics. These results are considered relevant for the use of this component in both military applications and space technology.",
journal = "IEEE Transactions on Nuclear Science",
title = "Radioactive reliability of gas filled surge arresters",
volume = "50",
number = "5",
pages = "1725-1731",
doi = "10.1109/TNS.2003.818269"
}

Lončar, B. B., Osmokrović, P. V.,& Stanković, S.. (2003). Radioactive reliability of gas filled surge arresters. in IEEE Transactions on Nuclear Science, 50(5), 1725-1731.
https://doi.org/10.1109/TNS.2003.818269

Lončar BB, Osmokrović PV, Stanković S. Radioactive reliability of gas filled surge arresters. in IEEE Transactions on Nuclear Science. 2003;50(5):1725-1731.
doi:10.1109/TNS.2003.818269 .

Lončar, Boris B., Osmokrović, Predrag V., Stanković, Srboljub, "Radioactive reliability of gas filled surge arresters" in IEEE Transactions on Nuclear Science, 50, no. 5 (2003):1725-1731,
https://doi.org/10.1109/TNS.2003.818269 . .

TY  - JOUR
AU  - Osmokrović, Predrag V.
AU  - Lončar, Boris B.
AU  - Stanković, Srboljub
PY  - 2002
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2607
AB  - This paper presents an alternative approach aimed toward improvement of protective characteristics of gas-filled surge arresters (GFSA). Although so far GFSA with built-in radioactive sources proved to have superior protective characteristics, environmental concerns often challenge functional benefits. Experimental results show that a hollow cathode used in GFSA (no radioactive sources), offers significant improvement of protective characteristics as compared to classical designs. A number of theoretical predictions and conclusions are confirmed experimentally.
T2  - IEEE Transactions on Plasma Science
T1  - Investigation of the optimal method for improvement of the protective characteristics of gas-filled surge arresters - With/without the built-in radioactive sources
VL  - 30
IS  - 5
SP  - 1876
EP  - 1880
DO  - 10.1109/TPS.2002.805327
ER  - 

@article{
author = "Osmokrović, Predrag V. and Lončar, Boris B. and Stanković, Srboljub",
year = "2002",
abstract = "This paper presents an alternative approach aimed toward improvement of protective characteristics of gas-filled surge arresters (GFSA). Although so far GFSA with built-in radioactive sources proved to have superior protective characteristics, environmental concerns often challenge functional benefits. Experimental results show that a hollow cathode used in GFSA (no radioactive sources), offers significant improvement of protective characteristics as compared to classical designs. A number of theoretical predictions and conclusions are confirmed experimentally.",
journal = "IEEE Transactions on Plasma Science",
title = "Investigation of the optimal method for improvement of the protective characteristics of gas-filled surge arresters - With/without the built-in radioactive sources",
volume = "30",
number = "5",
pages = "1876-1880",
doi = "10.1109/TPS.2002.805327"
}

Osmokrović, P. V., Lončar, B. B.,& Stanković, S.. (2002). Investigation of the optimal method for improvement of the protective characteristics of gas-filled surge arresters - With/without the built-in radioactive sources. in IEEE Transactions on Plasma Science, 30(5), 1876-1880.
https://doi.org/10.1109/TPS.2002.805327

Osmokrović PV, Lončar BB, Stanković S. Investigation of the optimal method for improvement of the protective characteristics of gas-filled surge arresters - With/without the built-in radioactive sources. in IEEE Transactions on Plasma Science. 2002;30(5):1876-1880.
doi:10.1109/TPS.2002.805327 .

Osmokrović, Predrag V., Lončar, Boris B., Stanković, Srboljub, "Investigation of the optimal method for improvement of the protective characteristics of gas-filled surge arresters - With/without the built-in radioactive sources" in IEEE Transactions on Plasma Science, 30, no. 5 (2002):1876-1880,
https://doi.org/10.1109/TPS.2002.805327 . .

TY  - JOUR
AU  - Lončar, Boris B.
AU  - Osmokrović, Predrag V.
AU  - Stanković, Srboljub
PY  - 2002
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2608
AB  - In this paper, we present temperature stability investigations of different overvoltage protection components employed in low-voltage applications. The following components have been examined: transient suppresser diodes, metal-oxide varistors (MOVs), gas-filled surge arresters (GFSAs), and polycarbonate capacitors. The aim of the research presented here is to identify the effectiveness of the overvoltage protection as a function of temperature. Experimental results,show that GFSAs have rather stabile operational characteristics in a wide temperature range (from -90degreesC to +210degreesC). As for MOVs they exhibit certain improvement of their protective characteristics at higher temperatures. Experimental results are backed tip by I theoretical explanations.
T2  - IEEE Transactions on Plasma Science
T1  - Temperature stability of components for overvoltage protection of low-voltage systems
VL  - 30
IS  - 5
SP  - 1881
EP  - 1885
DO  - 10.1109/TPS.2002.805329
ER  - 

@article{
author = "Lončar, Boris B. and Osmokrović, Predrag V. and Stanković, Srboljub",
year = "2002",
abstract = "In this paper, we present temperature stability investigations of different overvoltage protection components employed in low-voltage applications. The following components have been examined: transient suppresser diodes, metal-oxide varistors (MOVs), gas-filled surge arresters (GFSAs), and polycarbonate capacitors. The aim of the research presented here is to identify the effectiveness of the overvoltage protection as a function of temperature. Experimental results,show that GFSAs have rather stabile operational characteristics in a wide temperature range (from -90degreesC to +210degreesC). As for MOVs they exhibit certain improvement of their protective characteristics at higher temperatures. Experimental results are backed tip by I theoretical explanations.",
journal = "IEEE Transactions on Plasma Science",
title = "Temperature stability of components for overvoltage protection of low-voltage systems",
volume = "30",
number = "5",
pages = "1881-1885",
doi = "10.1109/TPS.2002.805329"
}

Lončar, B. B., Osmokrović, P. V.,& Stanković, S.. (2002). Temperature stability of components for overvoltage protection of low-voltage systems. in IEEE Transactions on Plasma Science, 30(5), 1881-1885.
https://doi.org/10.1109/TPS.2002.805329

Lončar BB, Osmokrović PV, Stanković S. Temperature stability of components for overvoltage protection of low-voltage systems. in IEEE Transactions on Plasma Science. 2002;30(5):1881-1885.
doi:10.1109/TPS.2002.805329 .

Lončar, Boris B., Osmokrović, Predrag V., Stanković, Srboljub, "Temperature stability of components for overvoltage protection of low-voltage systems" in IEEE Transactions on Plasma Science, 30, no. 5 (2002):1881-1885,
https://doi.org/10.1109/TPS.2002.805329 . .

TY  - JOUR
AU  - Osmokrović, Predrag V.
AU  - Lončar, Boris B.
AU  - Stanković, Srboljub
AU  - Vasić, Aleksandra
PY  - 2002
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2592
AB  - The aim of this work is examining the influence of the number of the activation-over-voltage pulses to the aging of over-voltage protection elements. Both non-linear (gas-filled surge arresters (GFSA), varistors, over-voltage diodes) and linear (capacitors-constituents of filters) over-voltage protection elements were tested. The instruments employed allow reliable measurements, 1000 consecutive activation were tested. The double-exponential current pulse (amplitude I-1(max) = 13 A, I-2(max) = 16 A, rise time T-1 = 8 mus, fall time T-2 = 20 mus) for non-linear elements and a double-exponential over-voltage pulse (rise time T-1 = 1.2 mus, fall time T-2 = 50 mus) of the amplitude U-1(max) = 320 V, U-2(max) = 480 V and U-3(max) = 640 V for capacitors were used. The experimental results show that the over-voltage diodes are the most reliable elements in view of characteristic modifications that are consequence of aging. However, it was observed that varistors, GFSA and capacitors undergo noticeable changes in characteristics. (C) 2002 Elsevier Science Ltd. All rights reserved.
T2  - Microelectronics Reliability
T1  - Aging of the over-voltage protection elements caused by over-voltages
VL  - 42
IS  - 12
SP  - 1959
EP  - 1966
DO  - 10.1016/S0026-2714(02)00240-8
ER  - 

@article{
author = "Osmokrović, Predrag V. and Lončar, Boris B. and Stanković, Srboljub and Vasić, Aleksandra",
year = "2002",
abstract = "The aim of this work is examining the influence of the number of the activation-over-voltage pulses to the aging of over-voltage protection elements. Both non-linear (gas-filled surge arresters (GFSA), varistors, over-voltage diodes) and linear (capacitors-constituents of filters) over-voltage protection elements were tested. The instruments employed allow reliable measurements, 1000 consecutive activation were tested. The double-exponential current pulse (amplitude I-1(max) = 13 A, I-2(max) = 16 A, rise time T-1 = 8 mus, fall time T-2 = 20 mus) for non-linear elements and a double-exponential over-voltage pulse (rise time T-1 = 1.2 mus, fall time T-2 = 50 mus) of the amplitude U-1(max) = 320 V, U-2(max) = 480 V and U-3(max) = 640 V for capacitors were used. The experimental results show that the over-voltage diodes are the most reliable elements in view of characteristic modifications that are consequence of aging. However, it was observed that varistors, GFSA and capacitors undergo noticeable changes in characteristics. (C) 2002 Elsevier Science Ltd. All rights reserved.",
journal = "Microelectronics Reliability",
title = "Aging of the over-voltage protection elements caused by over-voltages",
volume = "42",
number = "12",
pages = "1959-1966",
doi = "10.1016/S0026-2714(02)00240-8"
}

Osmokrović, P. V., Lončar, B. B., Stanković, S.,& Vasić, A.. (2002). Aging of the over-voltage protection elements caused by over-voltages. in Microelectronics Reliability, 42(12), 1959-1966.
https://doi.org/10.1016/S0026-2714(02)00240-8

Osmokrović PV, Lončar BB, Stanković S, Vasić A. Aging of the over-voltage protection elements caused by over-voltages. in Microelectronics Reliability. 2002;42(12):1959-1966.
doi:10.1016/S0026-2714(02)00240-8 .

Osmokrović, Predrag V., Lončar, Boris B., Stanković, Srboljub, Vasić, Aleksandra, "Aging of the over-voltage protection elements caused by over-voltages" in Microelectronics Reliability, 42, no. 12 (2002):1959-1966,
https://doi.org/10.1016/S0026-2714(02)00240-8 . .

TY  - JOUR
AU  - Lončar, Boris B.
AU  - Osmokrović, Predrag V.
AU  - Stojanović, M.
AU  - Stanković, Srboljub
PY  - 2001
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2427
AB  - In this study, we examine the reliability of erasable programmable read only memory (EPROM) and electrically erasable programmable read only memory (EEPROM) components under the influence of gamma radiation. This problem has significance in military industry and space technology Total dose results are presented for the JL 27C512D EPROM and 28C64C EEPROM components. There is evidence that EPROM components have better radioactive reliability than EEPROM components. Also, the changes to the EPROM are reversible, and after erasing and reprogramming all EPROM components are functional. On the other hand, changes to the EEPROM are irreversible, and under the influence of gamma radiation, all EEPROM components became permanently nonfunctional. The obtained results are analyzed and explained via the interaction of gamma radiation with oxide layers.
T2  - Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes and Review Papers
T1  - Radioactive reliability of programmable memories
VL  - 40
IS  - 2B
SP  - 1126
EP  - 1129
DO  - 10.1143/JJAP.40.1126
ER  - 

@article{
author = "Lončar, Boris B. and Osmokrović, Predrag V. and Stojanović, M. and Stanković, Srboljub",
year = "2001",
abstract = "In this study, we examine the reliability of erasable programmable read only memory (EPROM) and electrically erasable programmable read only memory (EEPROM) components under the influence of gamma radiation. This problem has significance in military industry and space technology Total dose results are presented for the JL 27C512D EPROM and 28C64C EEPROM components. There is evidence that EPROM components have better radioactive reliability than EEPROM components. Also, the changes to the EPROM are reversible, and after erasing and reprogramming all EPROM components are functional. On the other hand, changes to the EEPROM are irreversible, and under the influence of gamma radiation, all EEPROM components became permanently nonfunctional. The obtained results are analyzed and explained via the interaction of gamma radiation with oxide layers.",
journal = "Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes and Review Papers",
title = "Radioactive reliability of programmable memories",
volume = "40",
number = "2B",
pages = "1126-1129",
doi = "10.1143/JJAP.40.1126"
}

Lončar, B. B., Osmokrović, P. V., Stojanović, M.,& Stanković, S.. (2001). Radioactive reliability of programmable memories. in Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes and Review Papers, 40(2B), 1126-1129.
https://doi.org/10.1143/JJAP.40.1126

Lončar BB, Osmokrović PV, Stojanović M, Stanković S. Radioactive reliability of programmable memories. in Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes and Review Papers. 2001;40(2B):1126-1129.
doi:10.1143/JJAP.40.1126 .

Lončar, Boris B., Osmokrović, Predrag V., Stojanović, M., Stanković, Srboljub, "Radioactive reliability of programmable memories" in Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes and Review Papers, 40, no. 2B (2001):1126-1129,
https://doi.org/10.1143/JJAP.40.1126 . .

TY  - JOUR
AU  - Osmokrović, Predrag V.
AU  - Stojanović, M.
AU  - Lončar, Boris B.
AU  - Kartalović, Nenad M.
AU  - Krivokapić, I.
PY  - 1998
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2150
AB  - Aim of this work is to examine the over-voltage protection under the ionizing radiation influence. The use of modern electronic devices (nuclear, military and space technology) in the conditions of ionizing radiation brings up the question of radioactive resistance of electronic components and over-voltage protection components. The question of reliability of these components under the influence of ionizing radiation is also a relevant one, The entire effects of radiation, which cause the irreversible changes of the material characteristics, are defined as the dosage or integral effects, The resistance of the over-voltage material (the Transient Suppresser Diodes (TSD), Metaloxide Varistors, Gas Filled Surge Arresters (GFSA) and Polycarbon Capacitors) subjected to influence of n perpendicular to gamma radiation caused by californium source was examined in order to determine the radiation effects. It was determined that TSD are highly sensitive to the radiation, The radiation effects on Metaloxide Varistors are similar to the effects on the TSD, GFSA showed the temporary characteristics improvement. It was determined that the Polycarbon Capacitor capacity decreases under the influence of radiation. The obtained results are explained theoretically. (C) 1998 Elsevier Science B.V.
T2  - Nuclear Instruments and Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms
T1  - Radioactive resistance of elements for over-voltage protection of low-voltage systems
VL  - 140
IS  - 1-2
SP  - 143
EP  - 151
DO  - 10.1016/S0168-583X(97)00921-X
ER  - 

@article{
author = "Osmokrović, Predrag V. and Stojanović, M. and Lončar, Boris B. and Kartalović, Nenad M. and Krivokapić, I.",
year = "1998",
abstract = "Aim of this work is to examine the over-voltage protection under the ionizing radiation influence. The use of modern electronic devices (nuclear, military and space technology) in the conditions of ionizing radiation brings up the question of radioactive resistance of electronic components and over-voltage protection components. The question of reliability of these components under the influence of ionizing radiation is also a relevant one, The entire effects of radiation, which cause the irreversible changes of the material characteristics, are defined as the dosage or integral effects, The resistance of the over-voltage material (the Transient Suppresser Diodes (TSD), Metaloxide Varistors, Gas Filled Surge Arresters (GFSA) and Polycarbon Capacitors) subjected to influence of n perpendicular to gamma radiation caused by californium source was examined in order to determine the radiation effects. It was determined that TSD are highly sensitive to the radiation, The radiation effects on Metaloxide Varistors are similar to the effects on the TSD, GFSA showed the temporary characteristics improvement. It was determined that the Polycarbon Capacitor capacity decreases under the influence of radiation. The obtained results are explained theoretically. (C) 1998 Elsevier Science B.V.",
journal = "Nuclear Instruments and Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms",
title = "Radioactive resistance of elements for over-voltage protection of low-voltage systems",
volume = "140",
number = "1-2",
pages = "143-151",
doi = "10.1016/S0168-583X(97)00921-X"
}

Osmokrović, P. V., Stojanović, M., Lončar, B. B., Kartalović, N. M.,& Krivokapić, I.. (1998). Radioactive resistance of elements for over-voltage protection of low-voltage systems. in Nuclear Instruments and Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms, 140(1-2), 143-151.
https://doi.org/10.1016/S0168-583X(97)00921-X

Osmokrović PV, Stojanović M, Lončar BB, Kartalović NM, Krivokapić I. Radioactive resistance of elements for over-voltage protection of low-voltage systems. in Nuclear Instruments and Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. 1998;140(1-2):143-151.
doi:10.1016/S0168-583X(97)00921-X .

Osmokrović, Predrag V., Stojanović, M., Lončar, Boris B., Kartalović, Nenad M., Krivokapić, I., "Radioactive resistance of elements for over-voltage protection of low-voltage systems" in Nuclear Instruments and Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms, 140, no. 1-2 (1998):143-151,
https://doi.org/10.1016/S0168-583X(97)00921-X . .