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Automotive drive cycles have existed since the 1960s. They started as requirements as being solely used for emissions testing. During the past decade, they became popular with scientists and researchers in the testing of electrochemical vehicles and power devices. They help simulate realistic driving scenarios anywhere from system to component-level design. This paper aims to discuss the complete history of these drive cycles and their validity when used in an electrochemical propulsion scenario, namely with the use of proton exchange membrane fuel cells (PEMFC) and lithium-ion batteries. The differences between two categories of drive cycles, modal and transient, were compared; and further discussion was provided on why electrochemical vehicles need to be designed and engineered with transient drive cycles instead of modal. Road-going passenger vehicles are the main focus of this piece. Similarities and differences between aviation and marine drive cycles are briefly mentioned and compared and contrasted with road cycles. The construction of drive cycles and how they can be transformed into a 'power cycle' for electrochemical device sizing purposes for electrochemical vehicles are outlined; in addition, how one can use power cycles to size electrochemical vehicles of various vehicle architectures are suggested, with detailed explanations and comparisons of these architectures. A concern with using conventional drive cycles for electrochemical vehicles is that these types of vehicles behave differently compared to combustion-powered vehicles, due to the use of electrical motors rather than internal combustion engines, causing different vehicle behaviours and dynamics. The challenges, concerns, and validity of utilising 'general use' drive cycles for electrochemical purposes are discussed and critiqued. [ABSTRACT FROM AUTHOR]

For accurate and efficient control performance of electrical drives, precise values of phase voltages are required. In order to achieve control of the electric drive, the development of mathematical models of the system and its parts is often approached. Data-driven modeling using artificial intelligence can often be unprofitable due to the large amount of computing resources required. To overcome this problem, the idea is to investigate if a genetic programming–symbolic regressor (GPSR) algorithm could be used to obtain simple symbolic expressions which could estimate the mean phase voltages (black-box inverter model) and duty cycles (black-box compensation scheme) with high accuracy using a publicly available dataset. To obtain the best symbolic expressions using GPSR, a random hyperparameter search method and 5-fold cross-validation were developed. The best symbolic expressions were chosen based on their estimation performance, which was measured using the coefficient of determination ( R 2 ), mean absolute error ( M A E ), and root mean squared error ( R M S E ). The best symbolic expressions for the estimation of mean phase voltages achieved R 2 , M A E , and R M S E values of 0.999, 2.5, and 2.8, respectively. The best symbolic expressions for the estimation of duty cycles achieved R 2 , M A E , and R M S E values of 0.9999, 0.0027, and 0.003, respectively. The originality of this work lies in the application of the GPSR algorithm, which, based on a mathematical equation it generates, can estimate the value of mean phase voltages and duty cycles in a three-phase inverter. Using the obtained model, it is possible to estimate the given aforementioned values. Such high-performing estimation represents an opportunity to replace expensive online equipment with a cheaper, more precise, and faster approach, such as a GPSR-based model. The presented procedure shows that the symbolic expression for the accurate estimation of mean phase voltages and duty cycles can be obtained using the GPSR algorithm. [ABSTRACT FROM AUTHOR]

Automotive drive cycles have existed since the 1960s. They started as requirements as being solely used for emissions testing. During the past decade, they became popular with scientists and researchers in the testing of electrochemical vehicles and power devices. They help simulate realistic driving scenarios anywhere from system to component-level design. This paper aims to discuss the complete history of these drive cycles and their validity when used in an electrochemical propulsion scenario, namely with the use of proton exchange membrane fuel cells (PEMFC) and lithium-ion batteries. The differences between two categories of drive cycles, modal and transient, were compared; and further discussion was provided on why electrochemical vehicles need to be designed and engineered with transient drive cycles instead of modal. Road-going passenger vehicles are the main focus of this piece. Similarities and differences between aviation and marine drive cycles are briefly mentioned and compared and contrasted with road cycles. The construction of drive cycles and how they can be transformed into a ‘power cycle’ for electrochemical device sizing purposes for electrochemical vehicles are outlined; in addition, how one can use power cycles to size electrochemical vehicles of various vehicle architectures are suggested, with detailed explanations and comparisons of these architectures. A concern with using conventional drive cycles for electrochemical vehicles is that these types of vehicles behave differently compared to combustion-powered vehicles, due to the use of electrical motors rather than internal combustion engines, causing different vehicle behaviours and dynamics. The challenges, concerns, and validity of utilising ‘general use’ drive cycles for electrochemical purposes are discussed and critiqued.

• Titanium oxynitride films are sputter-deposited pulsing O 2 and N 2 independently. • Duty cycle of each reactive gas allows a precise control of the sputtering process. • Reactive sputtering alternates between elemental, oxidized and nitrided modes. • A smooth absorbent-to-transparent transition is obtained tuning both duty cycles. Titanium oxynitride thin films are deposited by DC reactive magnetron sputtering. A pure titanium target is sputtered in a reactive atmosphere composed of argon, oxygen and nitrogen gases. The oxygen mass flow rate as well as that of the nitrogen gas are both pulsed during the deposition time using an independent and rectangular signal for each reactive gas. A constant pulsing period T = 45 s is applied for both reactive gases and a delay time δ of 34 s between N 2 and O 2 injection times is set for all depositions. Oxygen and nitrogen duty cycles are systematically and independently changed from 0 to 100 % of their pulsing period. From real time measurements of the Ti target potential and total sputtering pressure, it is shown that the reactive process alternates between oxidized, nitrided and elemental sputtering modes as a function of the oxygen and nitrogen injection times. The full poisoning of the Ti target surface by oxygen and/or nitrogen can be avoided for some given ranges of O 2 and N 2 duty cycles. Deposition rates of titanium oxynitride films are substantially enhanced and can be adjusted between that of pure Ti and TiN films with a gradual transition of their electrical conductivity and optical transmittance in the visible range. These results support that titanium oxynitride compounds exhibiting absorbent to transparent behaviors can be precisely sputter-deposited by means of a two reactive gases pulsing process. [ABSTRACT FROM AUTHOR]

In this article, a parallel-circuit class-EF power amplifier with a shunt quarter-wave transmission-line for driving signals with arbitrary duty cycles is proposed and investigated. At the particular condition of duty cycle = 1/3, the values of the elements in the output network, as well as, some critical design parameters are analyzed and optimized. This leads to a series of significant improvements in the peak drain voltage (Vmax), the maximum operating frequency (fmax), and the power output capability (cp). Furthermore, in order to verify the advantage of the proposed new amplifier and its feasibility in realistic situations, a proof-of-concept circuit is designed and fabricated. Finally, at the operating frequency of 3.59 GHz, excellent performance has been achieved with the power-added efficiency of 79.9% and output power of 40.7 dBm. [ABSTRACT FROM AUTHOR]

A grid connected hybrid energy system combining wind turbine (WT) and photovoltaic (PV) array generating system with energy storage system to supply continuous power to the load using hybrid technique is exhibited in this dissertation. The proposed hybrid technique is the joint execution of both the binary chaotic crow search optimizer (BCCSO) with grey wolf optimizer and random forest algorithm (GWORFA) and hence it is named as BCCSO-GWORFA technique. The main aim of the proposal is to optimally track the maximum power point tracking (MPPT) and to maintain the power flow of the grid connected HRES. Here, the BCCSO-based MPPT procedure optimizes the exact duty cycles required for the DC-DC converter of the PV under partial shading conditions and WT system under variable speed conditions based on the voltage and current parameters. On the other hand, the grey wolf optimizer (GWO) learning procedure-based random forest algorithm (RFA) predicts the control signals of the voltage source inverter (VSI) based on the active and reactive power variations available in the load side. To predict the control parameters, the proposed technique considers power balance constraints like RES accessibility, storage element state of charge, and load side power demand. The proposed strategy is implemented in MATLAB/Simulink working platform. The performance of the HRES is assessed by utilizing the comparison analysis with the existing techniques. The comparison results invariably prove the proposed hybrid technique effectiveness and confirm its potential to solve the related issues with efficiency of 99.5%. [ABSTRACT FROM AUTHOR]

In this study, a three-port DC–DC converter is proposed based on quadratic boost converter. The proposed converter contains paths to enable the flow of power from input source to load and battery. Furthermore, it makes a path available to energise the load by the battery. The proposed converter has a bidirectional path using two additional switches and two diodes. Power flows from the input source and the battery to the load in a single-stage resulting in higher efficiency. The proposed converter has three switches and two duty cycles defined. By adjusting the duty cycles, maximum input power and output voltage can be regulated based on the input source power and the battery condition. To control the proposed converter, three operation modes are defined. In order to design the control system, the proposed converter is analysed and the small-signal models are obtained. Using a decoupling network for the integrated small-signal models, separated closed-loop controllers are designed. Finally, a prototype for the proposed converter is prepared to validate feasibility and effectiveness of the proposed converter and the control method by experimental results. [ABSTRACT FROM AUTHOR]

In the past years, forklift manufacturers have started to hybridise their products under the worldwide interest toward electrification. This is generally made starting from existing standard products, and converting them into hybrid versions, rather than start from scratch and designing fully new vehicles. This approach involves several gaps from the inaccurate evaluation of the powertrain architecture and relative energy management strategy, up to a rough sizing of components. Therefore, this study suggests a structured methodology to follow, aimed to properly design hybrid forklift trucks. The first step is the analysis of the conventional working machine to hybridise, identifying one set of duty cycles. Then, the design of the new powertrain architecture, with a proper energy management strategy, and the definition of a numerical simulation model realised through a multiphysics object‐oriented software package, to properly size the new powertrain components, and to verify energy and power flows. Finally, it is also presented a brief‐cost–benefit analysis, as last verification of the proposed methodology, to verify the cost‐effectiveness to bring the new products to the market. Results have shown the general feasibility of the operation since the significant reduction in fuel consumption is combined with sustainable costs of the new electrified components. [ABSTRACT FROM AUTHOR]

A dual input DC–DC converter with dual boost and integrated voltage multiplier cell operating at duty cycles larger than 0.5 is a necessity to achieve a high voltage gain for energy systems possessing two independent renewable energy resources. Output voltage regulation during load changes and input disturbances is the requisite of an energy system, which is achieved by the implementation of a suitable control action, which further requires the dynamic model of the converter. The modelling of this higher order converter with overlapping switching signals is complicated. The small‐signal transfer function model based on state‐space averaging followed by small‐signal linearisation is verified using MATLAB and powersim (PSIM). The output voltage to duty cycle transfer functions significantly contributes to representing the converter dynamics from which its right‐half s‐plane zero is analysed. Since it is a non‐minimum phase system, a dual loop control strategy is adopted. Voltage regulation and active current sharing are ensured from the simulation and experimental responses of the uncompensated and compensated systems. Further, from the derived integer‐order converter model a fractional controller is designed and its dynamic response is compared with the traditional controller. A 200 W prototype of the converter is developed, and the control is implemented using field‐programmable gate array. [ABSTRACT FROM AUTHOR]

Wireless sensor networks are appealing, largely because they do not need wired infrastructure, but it is precisely this feature that renders them energy-constrained. The duty cycle scheduling is perceived as a contributor to the energy efficiency of sensing. This paper developed a novel paradigm for modeling wireless sensor networks; in this context, an adaptive sensing scheduling strategy is proposed depending on event occurrence behavior, and the scheduling problem is framed as an optimization problem. The optimization objectives include reducing energy depletion and optimizing detection accuracy. We determine the explicit form of the objective function by numerical fitting and found that the objective function aggregated by the fitting functions is a bivariate multimodal function that favors the Fibonacci tree optimization algorithm. Then, with the optimal parameters optimized by the Fibonacci tree optimization algorithm, the scheduling scheme can be easily deployed, and it behaves consistently in the coming hours. The proposed “Fibonacci Tree Optimization Strategy” (“FTOS”) outperforms lightweight deployment-aware scheduling (LDAS), balanced-energy scheduling (BS), distributed self-spreading algorithm (DSS) and probing environment and collaborating adaptive sleeping (PECAS) in achieving the aforementioned scheduling objectives. The Fibonacci tree optimization algorithm has attained a better optimistic effect than the artificial bee colony (ABC) algorithm, differential evolution (DE) algorithm, genetic algorithm (GA) algorithm, particle swarm optimization (PSO) algorithm, and comprehensive learning particle swarm optimization (CLPSO) algorithm in multiple runs.

Here, a simplified predictive torque control strategy based on discrete duty cycle technology is proposed for the voltage source inverter permanent magnet synchronous motor drive system. Combining the discrete duty cycle technology, the candidate vectors are synthesised by two adjacent active vectors and zero vectors, and meanwhile, the duty cycles of the two adjacent active vectors and zero vectors are generated directly. Afterwards, an extended control set is constructed to improve the control accuracy of torque and flux. An inverted triangular matrix is constructed to store the duty cycle information, which corresponds to the row and column number of the elements. Also, the inverted triangle matrix is divided into three subregions according to the value of duty ratios. A cost function containing only the stator voltage vector error term is constructed and based on the geometric position of the reference voltage vector, the target region in the inverted triangle matrix is determined and the optimal vector is selected. So, the optimal vector prediction process and the duty cycle calculation process are combined into one, reducing the complexity of obtaining the optimal vector. Finally, the feasibility and effectiveness of the proposed algorithm are verified by experiments. [ABSTRACT FROM AUTHOR]

Millions of dedicated sensors are deployed in smart cities to enhance quality of urban living. Communication technologies are critical for connecting these sensors and transmitting events to sink. In control systems of mobile wireless sensor networks (MWSNs), mobile nodes are constantly moving to detect events, while static nodes constitute the communication infrastructure for information transmission. Therefore, how to communicate with sink quickly and effectively is an important research issue for control systems of MWSNs. In this paper, a communication scheme named first relay node selection based on fast response and multihop relay transmission with variable duty cycle (FRAVD) is proposed. The scheme can effectively reduce the network delay by combining first relay node selection with node duty cycles setting. In FRAVD scheme, first, for the first relay node selection, we propose a strategy based on fast response, that is, select the first relay node from adjacent nodes in the communication range within the shortest response time, and guarantee that the remaining energy and the distance from sink of the node are better than the average. Then for multihop data transmission of static nodes, variable duty cycle is introduced novelty, which utilizes the residual energy to improve the duty cycle of nodes in far-sink area, because nodes adopt a sleep-wake asynchronous mode, increasing the duty cycle can significantly improve network performance in terms of delays and transmission reliability. Our comprehensive performance analysis has demonstrated that compared with the communication scheme with fixed duty cycle, the FRAVD scheme reduces the network delay by 24.17%, improves the probability of finding first relay node by 17.68%, while also ensuring the network lifetime is not less than the previous researches, and is a relatively efficient low-latency communication scheme. [ABSTRACT FROM AUTHOR]

Idle times of shunting locomotives were measured in nineteen Polish industrial sidings and analyzed. The current locomotive owner’s regulations propose 30 min as the maximum idle time for shunting locomotives. Research shows that the size of a single idle time gap ranges from seconds (most frequent) to 4 h (during winter), but 95% of observed idle times are shorter than 4–11 min (for different types of locomotives). 75% of the idle times cases are less than 1.5 min (47 s if counted only for SM31 locomotive). We fit the distribution of the measured idle times to theoretical distributions, obtaining the best fit for the Pareto type II. If the diesel engine idle time lasts for 9 min then the probability that the given engine will stay in the idle mode for the subsequent 8 min is large, namely, greater than 0.6. These results go along with Weaver (2006). He concludes that if the locomotive idling lasts longer than 8 min then it is more energy efficient to turn off and restart a modern locomotive. Letting it idle for the whole time produces more emissions. If the frequent turning on and off does not reduce the engine life we propose to turn off the locomotive engine after 10 min of unnecessary idling. Automatic Engine Start Stop system (AESS) could (in addition to its main tasks) send reports to the locomotive owner if the engineer deactivates this system too many times. [ABSTRACT FROM AUTHOR]

Wireless visual sensor networks (WVSNs) are composed of a large number of visual sensor nodes covering a specific geographical region. This paper addresses the target detection problem within WVSNs where visual sensor nodes are left unattended for long-term deployment. As battery energy is a critical issue it is always challenging to maximize the network’s lifetime. In order to reduce energy consumption, nodes undergo cycles of active-sleep periods that save their battery energy by switching sensor nodes ON and OFF, according to predefined duty cycles. Moreover, adaptive compressive sensing is expected to dynamically reduce the size of transmitted data through the wireless channel, saving communication bandwidth and consequently saving energy. This paper derives for the first time an analytical framework for selecting node’s duty cycles and dynamically choosing the appropriate compression rates for the captured images and videos based on their sparsity nature. This reduces energy waste by reaching the maximum compression rate for each dataset without compromising the probability of detection. Experiments were conducted on different standard datasets resembling different scenes; indoor and outdoor, for single and multiple targets detection. Moreover, datasets were chosen with different sparsity levels to investigate the effect of sparsity on the compression rates. Results showed that by selecting duty cycles and dynamically choosing the appropriate compression rates, the desired performance of detection can be achieved with adaptive CS and at the same time saving energy, where the proposed framework results in an 70% on average energy saving as compared to transmitting the captured image without CS. [ABSTRACT FROM AUTHOR]

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The article focuses on characterization of leak rates under high static and cyclic pressure loads in thermoplastic barrier seals used in gas lift valves. The objective of the study is to validate the seal design for gas lift valves and check if its sealing material would meet the stringent leakage requirements laid out in the Statoil standards. The Statoil has a stringent leakage requirement of ≤2 sccm with gases and a pressure drop of ≤1% of the applied pressure differential with liquids. For convenience of the study only the barrier check valve portion of the actual gas lift valve is tested. It includes a spring, check dart, a portion of the flow bore, a portion of the nose (housing the dart) and the check seal. For leak tests at pressures up to 2000 psi, a standard nitrogen bottle was used and for higher pressures up to 10,000 psi, a boost pump was employed. In addition, the test rig was designed to generate accelerated cyclic loads to study the effect of it on leakage characteristics of the seal. Finite element analysis (FEA) on the seal design under 100 and 10,000 psi validated the stress-strain states in seal and predicted the sealing contact pressures. It was observed that the new seal design satisfies the Statoil requirements after an initial pressure cycle. In addition, it is observed that leak rates are unaffected by the accelerated loading cycles. [ABSTRACT FROM AUTHOR]

High power impulse magnetron sputtering (HiPIMS) is a novel physical vapor deposition (PVD) technique. HiPIMS is a low-temperature process, giving well-adherent coatings, better quality films, and droplet-free deposition. It provides enhanced gas dissociation and highly ionized plasma by inputting a high power during short pulses to the target. The target material is therefore not only sputtered but also ionized during the deposition process. In this study, TiN thin films were deposited using a uni-polar mode HiPIMS process. Nitrogen was used as the reactive gas to deposit TiN along with Ar gas. The deposition of TiN films was investigated by varying the duty cycles from 2 to 10% to have peak power density ranging from 208 to 1064 W/cm 2 . A high peak power density was obtained at a low duty cycle. DC magnetron sputtered TiN thin film (duty cycle = 100%) was also deposited for comparison. We demonstrate that the HiPIMS deposited TiN thin film exhibits a denser structure and smoother surface at low duty cycles. It was also found that the intense ion bombardment at low duty cycles deteriorates the film structure and their mechanical properties. Moderate ion bombardment at a duty cycle of 4.5% gives the highest (111)/(200) intensity ratio and the highest amount of Ti N bonding. This results in a film having the highest hardness, elastic modulus, and corrosion resistance of 29.3 GPa, 388.2 GPa, and 1.56E+ 06 (Ω/cm 2 ), respectively. However, oxygen was found in the resulting films. [ABSTRACT FROM AUTHOR]

This paper presents a fast and generalized space vector pulse width modulation (SVPWM) scheme for any multilevel inverter. The SVPWM scheme generates all the available switching states and switching sequences based on two simple and general mappings, and calculates the duty cycles simply as if for a two-level SVPWM, thus independent of the level number of the inverter. Because the switching states, duty cycles, and switching sequences are all obtained by simple calculation in the proposed SVPWM scheme, no lookup table is needed and the scheme is computationally fast. The generalized method of generating the switching states (first mapping), calculating the duty cycles, and determining the switching sequence (second mapping) is described in this paper. The scheme is suitable for any reference vector with any modulation index, and can be conveniently extended to meet specific requirements, such as symmetric switching sequences. Compared with prior methods, the SVPWM scheme proposed in this paper provides two more degrees of freedom, i.e., the adjustable switching sequences and duty cycles, thus offering significant flexibility for optimizing the performance of multilevel inverters. The influence of redundant switching sequences in the output phase voltage of inverters is demonstrated for a nine-level inverter. This paper also thoroughly compares the proposed SVPWM scheme with prior methods. Both simulation and experimental results are given. [ABSTRACT FROM AUTHOR]

This letter proposes a current sensorless controller for balancing the power in the dc/dc stage of a cascaded multilevel converter based solid state transformer. It is revealed that the equalization of the active power component of duty cycles in the cascaded multilevel rectifier stage can be a good indicator of power balance in the dc/dc stage. Additionally, the power balance of the dc/dc stage can guarantee the voltage balance in the rectifier stage if the differences among the power devices are negligible. Based on this principle, a novel power balance controller without sensing any current in the dc/dc stage is proposed. In the end, experimental results in a seven-level three-stage solid state transformer are provided for verifying the proposed method. [ABSTRACT FROM AUTHOR]

The use of electrical predistortion in optical single-sideband (OSSB) transmission systems is proposed to extend the tolerance to fiber dispersion impairment. Due to the spectral properties of OSSB signals, a simple electrical dispersive line can be used to mitigate the fiber dispersion, reducing the complexity of electrical predistortion methods proposed recently for optical modulations other than OSSB. Carrier-suppressed and carrier-unsuppressed optical modulations can be compensated by such technique, extending the range compared to previously reported works on fiber dispersion mitigation after direct detection using OSSB signals, where only carrier-unsuppressed modulations can be effectively compensated. The use of electrical precompensation is investigated for three signaling formats: Nonreturn to zero, return to zero, and alternate mark inversion (AMI). Due to distortion occurring in the sideband suppression process, signaling formats with reduced duty cycles present improved performance as a consequence of enhanced tolerance to intersymbol interference. Using such formats with electrical predistortion, the reach limitation arises not from fiber dispersion but from nonlinear impairments and optical noise accumulation. Using AMI and ideal electrical predistortion, distances greater than 1200 km of standard single mode fiber are achieved at 10 Gb/s with bit error ratio (BER) lower than 10-12 , without using optical dispersion compensation. Introducing accurate models for the electrical dispersive lines, the transmission distance is reduced to 720 km for BER lower than 10-12 [ABSTRACT FROM PUBLISHER]

Wireless sensor networks are appealing, largely because they do not need wired infrastructure, but it is precisely this feature that renders them energy-constrained. The duty cycle scheduling is perceived as a contributor to the energy efficiency of sensing. This paper developed a novel paradigm for modeling wireless sensor networks; in this context, an adaptive sensing scheduling strategy is proposed depending on event occurrence behavior, and the scheduling problem is framed as an optimization problem. The optimization objectives include reducing energy depletion and optimizing detection accuracy. We determine the explicit form of the objective function by numerical fitting and found that the objective function aggregated by the fitting functions is a bivariate multimodal function that favors the Fibonacci tree optimization algorithm. Then, with the optimal parameters optimized by the Fibonacci tree optimization algorithm, the scheduling scheme can be easily deployed, and it behaves consistently in the coming hours. The proposed "Fibonacci Tree Optimization Strategy" ("FTOS") outperforms lightweight deployment-aware scheduling (LDAS), balanced-energy scheduling (BS), distributed self-spreading algorithm (DSS) and probing environment and collaborating adaptive sleeping (PECAS) in achieving the aforementioned scheduling objectives. The Fibonacci tree optimization algorithm has attained a better optimistic effect than the artificial bee colony (ABC) algorithm, differential evolution (DE) algorithm, genetic algorithm (GA) algorithm, particle swarm optimization (PSO) algorithm, and comprehensive learning particle swarm optimization (CLPSO) algorithm in multiple runs. [ABSTRACT FROM AUTHOR]

An average current‐sensing circuit integrated in a hybrid DC–DC buck converter is presented. Both the high‐side and the low‐side switch currents are fully sensed by detecting the filtered smooth voltage of the switch node, which maintains a substantially constant mode changing point and seamless transition between pulse width modulation (PWM) and pulse frequency modulation (PFM) under various duty cycles. The achieved mode changing point is almost independent of temperature and supply voltage. The proposed circuit is suitable for high‐frequency hybrid DC–DC applications. [ABSTRACT FROM AUTHOR]

We demonstrate a simple way of generating chirped and alternate-chirp return-to-zero signals of various duty cycles by means of a sinusoidally driven dual-drive Mach-Zehnder modulator. The amount of inherently bit-synchronized chirp is tuned by varying the imbalance of the drive signals' amplitudes or their relative delay. High temporal resolution measurements of the intensity and phase of the modulated optical field are obtained at 20 and 40 Gb/s using the spectrogram technique. [ABSTRACT FROM PUBLISHER]