scispace - formally typeset
Search or ask a question
Author

Vittorio Rizzoli

Bio: Vittorio Rizzoli is an academic researcher from University of Bologna. The author has contributed to research in topics: Nonlinear system & Harmonic balance. The author has an hindex of 26, co-authored 143 publications receiving 2723 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: A survey of modern nonlinear CAD techniques as applied to the specific field of microwave circuits shows that the various subjects are not just separate items, but rather can be chained in a strictly logical sequence.
Abstract: The authors present a survey of modern nonlinear CAD (computer-aided design) techniques as applied to the specific field of microwave circuits. A number of fundamental aspects of the nonlinear CAD problem, including simulation, optimization, intermodulation, frequency conversion, stability, and noise, are addressed and developed. For each one it is shown that either well-established CAD solutions are available, or at least a solution approach suitable for implementation in a general-purpose CAD environment can be outlined. Also, the discussion shows that the various subjects are not just separate items, but rather can be chained in a strictly logical sequence. Finally, an elementary treatment of vector processing is given, to show that supercomputers can handle the involved large-size numerical problems efficiently. >

314 citations

Journal ArticleDOI
TL;DR: In this article, the authors present a self-consistent set of algorithms for the numerical computation of noise effects in forced and autonomous nonlinear microwave circuits using piecewise harmonic balance.
Abstract: This paper presents a self-consistent set of algorithms for the numerical computation of noise effects in forced and autonomous nonlinear microwave circuits. The analysis relies upon the piecewise harmonic-balance method, and thus retains all the peculiar advantages of this technique, including general-purposeness in the widest sense. The noise simulation capabilities include any kind of forced or autonomous nonlinear circuit operated in a time-periodic large-signal steady state, as well as microwave mixers of arbitrary topology. The limitations of the traditional frequency-conversion approach to noise analysis are overcome. The analysis takes into account the thermal noise generated in the passive subnetwork, the noise contributions of linear and nonlinear active devices, and the noise injected by sinusoidal driving sources of known statistical properties. The nonlinear noise models of two representative families of microwave devices (FET's/HEMT's and Schottky-barrier diodes) are discussed in detail, and several applications are illustrated. >

199 citations

Journal Article
01 Jan 1991-Leukemia
TL;DR: Fifty-nine European teams have reported 919 autografts for the consolidation of acute myelocytic leukemia (AML) up to December 31, 1989, and the distribution for autologous bone marrow transplantation was 671 in first complete remission (CR1) and 196 in CR2.
Abstract: Fifty-nine European teams have reported 919 autografts for the consolidation of acute myelocytic leukemia (AML) up to December 31, 1989 The distribution for autologous bone marrow transplantation (ABMT) was 671 in first complete remission (CR1) and 196 in CR2 Pretransplantation regimes were: total-body irradiation (TBI), 456; busulfan plus cyclophosphamide (BU-CY) 174; marrow purging with mafosfamide, 269 (corresponding to 26% of all patients in CR1 and 41% in CR2) Patients autografted in CR1 with no high risk factor (standard risk) had a leukemia-free survival (LFS) and relapse rate at 7 years of 48 +/- 2 and 41 +/- 3%, respectively Of all the prognostic factors studied, only secondary leukemia was correlated with a poorer LFS (19 +/- 9% at 1 year) and a higher relapse rate (76 +/- 11%) (p less than 00001) For patients autografted in CR2, the LFS and relapse rate were 34 +/- 4 and 54 +/- 5% With the restriction of a shorter follow-up, the results achieved with the BU-CY combinations (LFS and relapse rate at 3 years, CR1 47 +/- 6 and 45 +/- 7%; CR2, 37 +/- 9 and 50 +/- 10%) did not differ from those with TBI or other chemotherapy combinations LFS and relapse rates were correlated with several pretransplant intervals: in CR1, patients reaching CR more rapidly (less than or equal to 40 days) had a better LFS (53 +/- 3 versus 42 +/- 3%; p = 003) and a lower relapse rate (46 +/- 3 versus 57 +/- 3%; p = 003) In patients autografted less than 3 months, 3-6 months and more than 6 months after CR, the LFS was 26 +/- 5, 49 +/- 3, and 55 +/- 4%, respectively, and the relapse rates 63 +/- 5, 38 +/- 3, and 36 +/- 4% (p less than 00001 for both) In CR2, patients autografted more than 18 months after the initial diagnosis had a better LFS (42 +/- 5 versus 24 +/- 5%; p less than 0001) and a lower relapse rate (45 +/- 6 versus 65 +/- 6%; p less than 0001) For those autografted less than 3 months, 3-6 months and more than 6 months after CR, the probability of LFS was 30 +/- 5, 30 +/- 7, and 50 +/- 9% (p = 006), respectively and the relapse rates 63 +/- 6, 50 +/- 8, and 36 +/- 8% (p = 001)(ABSTRACT TRUNCATED AT 400 WORDS)

145 citations

Journal ArticleDOI
TL;DR: The theoretical foundations and numerical performance of an advanced nonlinear circuit simulator based on the piecewise harmonic balance (HB) technique are discussed in this paper, where the exact computation of the Jacobian matrix for Newton-iteration based HB simulation and the related conversion-matrix technique for fast mixer analysis are formulated in a general form.
Abstract: The theoretical foundations and the numerical performance of an advanced nonlinear circuit simulator based on the piecewise harmonic-balance (HB) technique are discussed. The exact computation of the Jacobian matrix for Newton-iteration based HB simulation and the related conversion-matrix technique for fast mixer analysis are formulated in a general form. Convergence problems at high drive levels are solved by a parametric formulation of the device models coupled with an advanced norm-reducing iteration. A physics-based approximation is shown to allow the HB equations to be effectively decoupled in many practical cases, bringing large-sized jobs, such as pulsed-RF analysis, within the reach of ordinary workstations. The exact Jacobian is used in conjunction with an exact formula for the gradient of the objective function, to implement an efficient broadband nonlinear circuit optimization capability. Examples are presented. >

142 citations

Journal ArticleDOI
TL;DR: A powerful software tools for the simulation of nonlinear microwave circuits under single- or multiple-frequency excitation is described, with built-in facilities based on the multidimensional Fourier transform allowing a straightforward and unrestricted treatment of mixer and intermodulation problems.
Abstract: A powerful software tools for the simulation of nonlinear microwave circuits under single- or multiple-frequency excitation is described. The program operates in a truly general-purpose fashion, both circuit topology and active-device equivalent circuits being arbitrarily established by the user at the data entry level. Built-in facilities based on the multidimensional Fourier transform allow a straightforward and unrestricted treatment of mixer and intermodulation problems. The capabilities of the program are illustrated by a number of practical examples. >

110 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: The concept of a dose-response effect for cytarabine in patients with AML who are 60 years of age or younger is supported and the results with the high-dose schedule in this age group are comparable to those reported in similar patients who have undergone allogeneic bone marrow transplantation during a first remission.
Abstract: Background About 65 percent of previously untreated adults with primary acute myeloid leukemia (AML) enter complete remission when treated with cytarabine and an anthracycline. However, such responses are rarely durable when conventional postremission therapy is administered. Uncontrolled trials have suggested that intensive postremission therapy may prolong these complete remissions. Methods We treated 1088 adults with newly diagnosed AML with three days of daunorubicin and seven days of cytarabine and randomly assigned patients who had a complete remission to receive four courses of cytarabine at one of three doses: 100 mg per square meter of body-surface area per day for five days by continuous infusion, 400 mg per square meter per day for five days by continuous infusion, or 3 g per square meter in a 3-hour infusion every 12 hours (twice daily) on days 1, 3, and 5. All patients then received four courses of monthly maintenance treatment. Results Of the 693 patients who had a complete remission, 596 we...

1,370 citations

Journal ArticleDOI
TL;DR: In this paper, the authors developed a solid foundation for phase noise that is valid for any oscillator, regardless of operating mechanism, and established novel results about the dynamics of stable nonlinear oscillators in the presence of perturbations, both deterministic and random.
Abstract: Phase noise is a topic of theoretical and practical interest in electronic circuits, as well as in other fields, such as optics. Although progress has been made in understanding the phenomenon, there still remain significant gaps, both in its fundamental theory and in numerical techniques for its characterization. In this paper, we develop a solid foundation for phase noise that is valid for any oscillator, regardless of operating mechanism. We establish novel results about the dynamics of stable nonlinear oscillators in the presence of perturbations, both deterministic and random. We obtain an exact nonlinear equation for phase error, which we solve without approximations for random perturbations. This leads us to a precise characterization of timing jitter and spectral dispersion, for computing of which we have developed efficient numerical methods. We demonstrate our techniques on a variety of practical electrical oscillators and obtain good matches with measurements, even at frequencies close to the carrier, where previous techniques break down. Our methods are more than three orders of magnitude faster than the brute-force Monte Carlo approach, which is the only previously available technique that can predict phase noise correctly.

1,226 citations

Journal ArticleDOI
TL;DR: Autologous as well as allogeneic bone marrow transplantation results in better disease-free survival than intensive consolidation chemotherapy with high-dose cytarabine and daunorubicin.
Abstract: Background Allogeneic or autologous bone marrow transplantation and intensive consolidation chemotherapy are used to treat acute myelogenous leukemia in a first complete remission. Methods After induction treatment with daunorubicin and cytarabine, patients who had a complete remission received a first course of intensive consolidation chemotherapy, combining intermediate-dose cytarabine and amsacrine. Patients with an HLA-identical sibling were assigned to undergo allogeneic bone marrow transplantation; the others were randomly assigned to undergo autologous bone marrow transplantation (with unpurged bone marrow) or a second course of intensive chemotherapy, combining high-dose cytarabine and daunorubicin. Comparisons were made on the basis of the intention to treat. Results A total of 623 patients had a complete remission; 168 were assigned to undergo allogeneic bone marrow transplantation, and 254 were randomly assigned to one of the other two groups. Of these patients, 343 completed the treatment assi...

855 citations

Journal ArticleDOI
TL;DR: In this article, a city-wide RF spectral survey was undertaken from outside all of the 270 London Underground stations at street level, and four harvesters (comprising antenna, impedance-matching network, rectifier, maximum power point tracking interface, and storage element) were designed to cover four frequency bands from the largest RF contributors within the ultrahigh frequency (0.3-3 GHz) part of the frequency spectrum.
Abstract: RF harvesting circuits have been demonstrated for more than 50 years, but only a few have been able to harvest energy from freely available ambient (i.e., non-dedicated) RF sources. In this paper, our objectives were to realize harvester operation at typical ambient RF power levels found within urban and semi-urban environments. To explore the potential for ambient RF energy harvesting, a city-wide RF spectral survey was undertaken from outside all of the 270 London Underground stations at street level. Using the results from this survey, four harvesters (comprising antenna, impedance-matching network, rectifier, maximum power point tracking interface, and storage element) were designed to cover four frequency bands from the largest RF contributors (DTV, GSM900, GSM1800, and 3G) within the ultrahigh frequency (0.3-3 GHz) part of the frequency spectrum. Prototypes were designed and fabricated for each band. The overall end-to-end efficiency of the prototypes using realistic input RF power sources is measured; with our first GSM900 prototype giving an efficiency of 40%. Approximately half of the London Underground stations were found to be suitable locations for harvesting ambient RF energy using our four prototypes. Furthermore, multiband array architectures were designed and fabricated to provide a broader freedom of operation. Finally, an output dc power density comparison was made between all the ambient RF energy harvesters, as well as alternative energy harvesting technologies, and for the first time, it is shown that ambient RF harvesting can be competitive with the other technologies.

778 citations

Journal ArticleDOI
TL;DR: Clinical efforts are underway to target specific components of the translation apparatus or unique mRNA translation elements for cancer therapeutics to define a new understanding of the role of mRNA translation and protein synthesis in human cancer.
Abstract: Remarkable progress has been made in defining a new understanding of the role of mRNA translation and protein synthesis in human cancer. Translational control is a crucial component of cancer development and progression, directing both global control of protein synthesis and selective translation of specific mRNAs that promote tumour cell survival, angiogenesis, transformation, invasion and metastasis. Translational control of cancer is multifaceted, involving alterations in translation factor levels and activities unique to different types of cancers, disease stages and the tumour microenvironment. Several clinical efforts are underway to target specific components of the translation apparatus or unique mRNA translation elements for cancer therapeutics.

753 citations