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Understanding nuclear and electronic dynamics of molecular systems has advanced considerably by probing their nonlinear responses with a suitable sequence of pulses. Moreover, the ability to control crucial parameters of the excitation pulses, such as duration, sequence, frequency, polarization, slowly varying envelope, or carrier phase, has led to a variety of advanced time-resolved spectroscopic methodologies. Recently, two-dimensional electronic spectroscopy with ultrashort pulses has become a more and more popular tool since it allows to obtain information on energy and coherence transfer phenomena, line broadening mechanisms, or the presence of quantum coherences in molecular complexes. Here, we present a high fidelity two-dimensional electronic spectroscopy setup designed for molecular systems in solution. It incorporates the versatility of pulse-shaping methods to achieve full control on the amplitude and phase of the individual exciting and probing pulses. Selective and precise amplitude- and phase-modulation is shown and applied to investigate electronic dynamics in several reference molecular systems. [ABSTRACT FROM AUTHOR]

The dependence of periodic structures and ablated areas on temporal pulse shaping is studied upon irradiation of fused silica by femtosecond laser triple-pulse trains. Three types of periodic structures can be obtained by using pulse trains with designed pulse delays, in which the threedimensional nanopillar arrays with ~100-150 nm diameters and ~200 nm heights are first fabricated in one step. These nanopillars arise from the break of the ridges of ripples in the upper portion, which is caused by the split of orthogonal ripples in the bottom part. The localized transient electron dynamics and corresponding material properties are considered for the morphological observations. [ABSTRACT FROM AUTHOR]

This paper presents the implementation of 3D IR spectroscopy by adding a second pump beam to a two-beam 2D IR spectrometer. An independent mid-IR pulse shaper is used for each pump beam, which can be programmed to collect its corresponding dimension in either the frequency or time-domains. Due to the phase matching geometry employed here, absorptive 3D IR spectra are automatically obtained, since all four of the rephasing and non-rephasing signals necessary to generate absorptive spectra are collected simultaneously. Phase cycling is used to isolate the fifth-order from the third-order signals. The method is demonstrated on tungsten hexacarbonyl (W(CO)6) and dicarbonylacetylacetonato rhodium (I), for which the eigenstates are extracted up to the third excited state. Pulse shaping affords a high degree of control over 3D IR experiments by making possible mixed time- and frequency-domain experiments, fast data acquisition and straightforward implementation. [ABSTRACT FROM AUTHOR]

In a conventional radar system, the hardware cost increases with the sampling rate of the receiver. Sub‐Nyquist radar systems operate at lower sampling rates and hence reduce the hardware cost and complexity. A sub‐Nyquist radar system uses the knowledge of the transmit pulse shape to determine the targets. However, the pulse shape is often distorted in practice and unknown to the receiver. An alternative sub‐Nyquist radar system that uses multiple receiver was proposed that estimates the targets without knowledge of the pulse shape. In this demo, the authors build a hardware prototype to demonstrate the proposed multi‐receiver sub‐Nyquist radar. The proposed two‐receiver system with an unknown pulse has comparable pre‐forms to a conventional sub‐Nyquist system is shown. This paper shows a hardware demonstration of sub‐Nyquist sampling of finite‐rate‐of‐innovation signals when the basic pulse shape is unknown. The results are particularly interesting in radar imaging, where the transmit pulse is distorted while propagation and unknown at the receiver. [ABSTRACT FROM AUTHOR]

The most commonly used multicarrier modulation method in 802.11 wireless communication systems is Orthogonal Frequency Division Multiplexing (OFDM). However, OFDM is easily affected by Inter Symbol Interference (ISI). In this paper, different pulse shaping filters are employed in the OFDM system and three new filters are presented to further reduce ISI effects. The first one is a Modified Parametric Exponential Pulse (MPEXP) filter which employs a different transfer function that is implemented at the transmitter side. The second one is a Better Than Modified Flipped Exponential Pulse (BTMFEXP) filter which is derived by modifying the transfer function of Modified Flipped Exponential Pulse (MFEXP). The third one is a hybrid of BTMFEXP and MPEXP (HBTMFPEXP). Lastly, low complexity forms of the MFEXP and BTMFEXP, derived from Taylor Series, are implemented. The OFDM system was tested with the existing and proposed pulses over AWGN and Fading channels. The proposed filters show better Bit Error Rate (BER) performance. Under a high ISI level, BTMFEXP and HBTMFPEXP showed a gain of 0.23 and 0.57 dB respectively over MFEXP with AWGN channel. With a fading channel at high ISI level, the proposed BTMFEXP and HBTMFPEXP demonstrated a gain of 2.33 and 5.33 dB respectively over MFEXP. [ABSTRACT FROM AUTHOR]

Abstract Ce doped (Gd , La) 2 Si 2 O 7 (LaGPS) is a new scintillator which has high light output and is a promising candidate for high resolution radiation imaging detectors. Thus we developed a radiation imaging detector using a LaGPS plate combined with a position sensitive photomultiplier tube (PSPMT) and evaluated the performance. We found that the decay times of LaGPS were different with the types of radiations and the separations of the images of the different types of radiations were possible using pulse shape discrimination. The spatial resolution for Am-241 alpha particles (5.5 MeV) was better than 0.31 mm FWHM and the energy resolution was 11 % FWHM. The spatial resolution for Sr–Y-90 beta particles was ∼ 0.6 mm FWHM and those for Co-57 gamma photons (122 keV) and Cs-137 X-ray (∼ 35 keV) were better than 0.6 mm FWHM and ∼ 0.8 mm FWHM, respectively. The decay times for alpha particles, beta particles, and gamma photons were 143 ns, 124 ns, and 119 ns, respectively. With these different decay times, the separation of alpha particles and gamma photons or beta particles was possible using the pulse shape discrimination. We conclude that the developed LaGPS imaging detector has high resolution for all types of radiations and is also capable of the simultaneous imaging and separating the different types of radiations. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a System on Programmable Chip (SoPC) design of a digitizer to determine particle features in nuclear physics covering arrival time and energy also for pileup events. The preamplified pulses from the radiation detector are digitized with a rate of 125 Ms/s. Pulse triggering and arrival time is measured by analysis of the pulse output after CR-RC filtering. Trapezoidal pulse shaping is applied for pulse-height energy measure and noise suppression. A new method is presented for trapezoidal flat top height analysis to ease calibration of the trapezoidal pulse shaping filter. The presented method also improves pulse analysis in terms of pileup identification and false pulse rejection. Experimental results obtain a repetitive pulse rate of 50 kHz. The digitizer is able to detect pileup events with a delay between pulses down to few micro seconds. [ABSTRACT FROM AUTHOR]

Abstract The light yield (LY) and decay kinetics of a single crystal scintillator of Gd 3 Al 2 Ga 3 O 12 (GAGG):Ce were measured for 0.662 MeV γ - and 5.48 MeV α -rays between −100 °C and room temperature. As the temperature decreased, the LY increased by 20% for γ -rays, reaching its maximum at around −70 °C, and increased monotonously by 50% for α -rays. Both the rise and decay times increased gradually. Furthermore, the results indicate that pulse shape discrimination is most effective at room temperature. [ABSTRACT FROM AUTHOR]

An ultrafast spectrum programmable femtosecond laser may enhance the performance of a wide variety of scientific applications, e.g., multi-photon imaging. In this paper, we report a digital micromirror device (DMD)-based ultrafast pulse shaper, i.e., DUPS, for femtosecond laser arbitrary amplitude shaping — the first time a programmable binary device reported to shape the amplitudes of ultrafast pulses spectrum at up to 32 kHz rate over a broad wavelength range. The DUPS is highly efficient, compact, and low cost based on the use of a DMD in combination with a transmission grating. Spatial and temporal dispersion introduced by the DUPS is compensated by a quasi-4-f setup and a grating pair, respectively. Femtosecond pulses with arbitrary spectrum shapes, including rectangular, sawtooth, triangular, double-pulse, and exponential profile, have been demonstrated in our experiments. A feedback operation process is implemented in the DUPS to ensure a robust and repeatable shaping process. The total efficiency of the DUPS for amplitude shaping is measured to be 27%. [ABSTRACT FROM AUTHOR]

In this paper, we model $M\times N$ orthogonal time frequency space modulation (OTFS) over a $P$ -path doubly dispersive channel with delays less than $\tau _{\max }$ and Doppler shifts in the range $(\nu _{\min },\nu _{\max })$. We first derive in a simple matrix form the input–output relation in the delay-Doppler domain for practical (e.g., rectangular) pulse-shaping waveforms, next generalize it to arbitrary waveforms. This relation extends the original OTFS input–output approach, which assumes ideal pulse-shaping waveforms that are bi-orthogonal in both time and frequency. We show that the OTFS input–output relation has a simple sparse structure that enables one to use low-complexity detection algorithms. Different from previous work, only a single cyclic prefix is added at the end of the OTFS frame, significantly reducing the overhead, without incurring any penalty from the loss of bi-orthogonality of the pulse-shaping waveforms. Finally, we compare the OTFS performance with different pulse-shaping waveforms, and show that the reduction of out-of-band power may introduce nonuniform channel gains for the transmitted symbols, thus impairing the overall error performance. [ABSTRACT FROM AUTHOR]

In this paper, the problem of reducing the peak-to-average power ratio (PAPR) of a discrete Fourier transform spread orthogonal frequency-division multiplexing signal is considered for the transmission of BPSK symbols. In particular, a joint optimization of the constellation-rotation angle and the pulse-shaping vector is conducted with or without the allocation of additional sub-carriers. To avoid the exponential complexity required to evaluate the PAPR, a computationally efficient upper bound on the worst-case PAPR is derived and adopted as the objective function. Unlike conventional upper bounds, the proposed upper bound exploits the structure in the relative phase among symbol waveforms and incorporates the constellation-rotation effect. The signal-to-interference-plus-noise ratio (SINR) at the output of a constellation-derotating matched filter is also derived along with a generalized Nyquist criterion and adopted as the inequality constraint function. Then, joint optimizations are conducted through numerical search for various signal parameters and target SINRs. Surprisingly, the optimal rotation angle is neither 0 nor $\pi /2$. It is shown that the proposed combinations significantly outperform the existing combinations of the rotation angle and the shaping vector when the signal is amplified by a nonlinear power amplifier. [ABSTRACT FROM AUTHOR]

Nonlinear transmission lines (NLTLs) are passive networks with the capability of modulating baseband pulses. These networks are used for generating RF pulses at high-power levels. NLTLs have a unique performance in high-power RF pulse generation among all the generators based on the solid-state technology. A high-power rectangular pulse is injected to the line, gradually evolved into an oscillatory pulse while propagating through the network, and finally, in the form of a high-power RF pulse, is delivered to the load. Properly terminating an NLTL, in order to transfer the maximum available RF power to the load, is an important problem. In this paper, an accurate analysis is presented, which gives a closed-form formula for the output RF power in lossy NLTLs. Using this analysis, optimal resistive terminating load for RF applications of NLTLs is extracted. The output central frequency is also investigated in this paper. All the obtained theoretical results are verified by SPICE simulations and measurements in two implemented NLTLs. [ABSTRACT FROM AUTHOR]

Abstract The motivation of the present paper is to study the performance of EJ 299-33 scintillator in online and off-line analysis in high rate scattering for nuclear reaction experiments performed with heavy ions. An experiment was carried out inside the CHIMERA chamber using 24Mg beams at 71.5 MeV and 81 MeV impinging on 92ZrO 2 target. The plastic scintillator was backed by a photomultiplier tube and the anode pulses were digitized through 100 MHz GET electronics for the purpose of pulse shape discrimination (PSD) studies. Performances of the plastic scintillator have been tested with respect to PSD capabilities and energy spectra analysis under beam irradiations in a high background environment. [ABSTRACT FROM AUTHOR]

Recent developments in organic plastic scintillators capable of pulse shape discrimination (PSD) enable a breakthrough in discrimination between neutrons and gammas. Plastic scintillator detectors coupled with silicon photomultipliers (SiPMs) offer many advantages, such as lower power consumption, smaller volume, and especially insensitivity to magnetic fields, compared with conventional photomultiplier tubes (PMTs). A SensL SiPM has two outputs: a standard output and a fast output. It is known that the charge injected into the fast output electrode is typically approximately 2% of the total charge generated during the avalanche, whereas the charge injected into the standard output electrode is nearly 98% of the total. Fast signals from SiPMs exhibit better performance in terms of timing and time-correlated measurements compared with standard signals. The pulse duration of a standard signal is on the order of hundreds of nanoseconds, whereas the pulse duration of the main monopole waveform of a fast signal is a few tens of nanoseconds. Fast signals are traditionally thought to be suitable for photon counting at very high speeds but unsuitable for PSD due to the partial charge collection. Meanwhile, the standard outputs of SiPMs coupled with discriminating scintillators have yielded nice PSD performances, but there have been no reports on PSD using fast signals. Our analysis shows that fast signals can also provide discrimination if the rate of charge injection into the fast output electrode is fixed for each event, even though only a portion of the charge is collected. In this work, we achieved successful PSD using fast signals; meanwhile, using a coincidence timing window of less 3 nanoseconds between the readouts from both ends of the detector reduced the influence of the high SiPM dark current. We experimentally achieved good timing performance and PSD capability simultaneously. [ABSTRACT FROM AUTHOR]

Abstract: Visible light communication (VLC) is an emerging optical wireless communication, which combines lighting and communication simultaneously. In indoor VLC systems, the brightness of LEDs should be dimmed to a certain level to support the illumination function. In this article, we propose a novel dimming control scheme based on Reversed Unipolar Return‐to‐Zero (RURZ) coding and circular (7, 1) modulation. The dimming level is determined by the duty cycle ratio (DCR) of the RURZ codes. Contrary to traditional RZ coding, with the decrease of DCR, the component of high‐level signal in RURZ codes increases and could constantly keep LEDs on. Therefore, when the DCR is smaller, the time that the LED is on keeps longer and the illumination efficiency is higher. A special shaped 8‐QAM modulation scheme called circular (7, 1) is employed to obtain a wider dimming range and higher communication quality for its superiority in operation range and bit error ratio (BER) performance. Furthermore, pulse shaping technology is utilized to suppress the wide spectrum extended by RURZ coding and increase the spectral efficiency (SE) and the data rate. Theoretical analysis and experimental investigation demonstrate that the RURZ coded and circular (7, 1) modulated VLC system could achieve a wide dimming range with high illumination efficiency and high communication speed. An illumination efficiency improvement of 0.63 is successfully achieved at 30% DCR with a data rate of 1.35 GB/s over 1 m free space transmission. [ABSTRACT FROM AUTHOR]

The coherent amplification network (CAN) aims at developing a laser system based on the coherent combination of multiple laser beams, which are produced through a network of high beam quality optical fiber amplifiers. For the front-end sources of high power laser facilities, single-mode linearly polarized beams in the nanosecond time scale are required. According to these two requirements, a millijoule polarized fiber laser system was studied. Using polarization maintaining Ytterbium-fiber laser system as the seed, 10-μm core diameter Yb-doped fiber amplifier as the first-stage power amplifier and 40-μm core diameter polarizing photonic crystal fiber (PCF) as the second-stage power amplifier, the all-fiber laser system output 1.06-mJ energy at 10 ns with diffraction limited mode quality. Using 85-μm core diameter rod-type PCF as the third-stage power amplifier, 2.5-mJ energy at 10-ns pulse width was obtained with better than 500:1 peak-to-foot pulse shaping ability and single-mode beam quality. The energy fluctuation of the system was 1.3% (rms) with 1-mJ output in an hour. This fiber laser system has the advantages of high beam quality, versatile pulse shaping ability, good stability, small volume, and free of maintenance, which can be used in many applications. [ABSTRACT FROM AUTHOR]

High‐precision measurement of X‐ray spectra is affected by the statistical fluctuation of the X‐ray beam under low‐counting‐rate conditions. It is also limited by counting loss resulting from the dead‐time of the system and pile‐up pulse effects, especially in a high‐counting‐rate environment. In this paper a detection system based on a FAST‐SDD detector and a new kind of unit impulse pulse‐shaping method is presented, for counting‐loss correction in X‐ray spectroscopy. The unit impulse pulse‐shaping method is evolved by inverse deviation of the pulse from a reset‐type preamplifier and a C‐R shaper. It is applied to obtain the true incoming rate of the system based on a general fast–slow channel processing model. The pulses in the fast channel are shaped to unit impulse pulse shape which possesses small width and no undershoot. The counting rate in the fast channel is corrected by evaluating the dead‐time of the fast channel before it is used to correct the counting loss in the slow channel. [ABSTRACT FROM AUTHOR]

We theoretically study the effects of the temporal intensity profile of the initial pulse on the nonlinear propagation spectral compression process arising from nonlinear propagation in an optical fibre. Various linearly chirped input pulse profiles are considered, and their dynamics is explained with the aid of time-frequency representations. While initially parabolic-shaped pulses show enhanced spectral compression compared to Gaussian pulses, no significant spectral narrowing occurs when initially super-Gaussian pulses are used. Triangular pulses lead to a spectral interference phenomenon similar to the Fresnel bi-prism experiment. [ABSTRACT FROM AUTHOR]

A high-speed, high-sensitivity and compact two-dimensional infrared (2D-IR) spectrometer based on 100 kHz Yb:KGW regenerative amplifier technology is described and demonstrated. The setup is three color, using an independent pump OPA and two separately tunable probe OPAs. The spectrometer uses 100 kHz acousto-optic pulse shaping on the pump beam for rapid 2D-IR acquisitions. The shot-to-shot stability of the laser system yields excellent signal-to-noise figures (∼10 μOD noise on 5000 laser shots). We show that the reduced bandwidth of the Yb:KGW amplifiers in comparison with conventional Ti:sapphire systems does not compromise the ability of the setup to generate high-quality 2D-IR data. Instrument responses of <300 fs are demonstrated and 2D-IR data presented for several systems of interest to physical chemists, showing spectral diffusion in NaSCN, amide I and II bands of a β sheet protein and DNA base-pair-backbone couplings. Overall, the increased data acquisition speed, intrinsic stability, and robustness of the Yb:KGW lasers are a significant step forward for 2D-IR spectroscopy. [ABSTRACT FROM AUTHOR]

Cadmium--zinc--telluride (CZT) arrays with photon-counting and energyresolving capabilities are widely proposed for next-generation X-ray imaging systems. This work presents the performance of a 2 mm-thick CZT pixel detector, with pixel pitches of 500 and 250 µm, dc coupled to a fast and low-noise ASIC (PIXIE ASIC), characterized only by the preamplifier stage. A custom 16-channel digital readout electronics was used, able to digitize and process continuously the signals from each output ASIC channel. The digital system performs on-line fast pulse shape and height analysis, with a low dead-time and reasonable energy resolution at both low and high fluxes. The spectroscopic response of the system to photon energies below (109Cd source) and above (241Am source) the K-shell absorption energy of the CZT material was investigated, with particular attention to the mitigation of charge sharing and pile-up. The detector allows high bias voltage operation (>5000 V cm-1) and good energy resolution at moderate cooling (3.5% and 5% FWHM at 59.5 keV for the 500 and 250 µm arrays, respectively) by using fast pulse shaping with a low dead-time (300 ns). Charge-sharing investigations were performed using a fine time coincidence analysis (TCA), with very short coincidence time windows up to 10 ns. For the 500 mm pitch array (250 µm pitch array), sharing percentages of 36% (52%) and 60% (82%) at 22.1 and 59.5 keV, respectively, were measured. The potential of the pulse shape analysis technique for chargesharing detection for corner/border pixels and at high rate conditions (250 kcps pixel-1), where the TCA fails, is also shown. Measurements demonstrated that significant amounts of charge are lost for interactions occurring in the volume of the inter-pixel gap. This charge loss must be accounted for in the correction of shared events. These activities are within the framework of an international collaboration on the development of energyresolved photon-counting systems for high-flux energy-resolved X-ray imaging (1-140 keV). [ABSTRACT FROM AUTHOR]

Discrete Cosine Transform based Single carrier frequency division multiple access (DCT-SCFDMA) is a prominent technique for providing high data rates in multimedia services. It also provides high Quality of Service to the users by mitigating the fading of signals. But High peak-to-average power ratio (PAPR) is a technical challenge which reduces the efficiency of RF power amplifiers. In this article, a novel joint scheme of PAPR reduction method is proposed and analyzed based on pulse shaping and absolute exponential companding (AEXP) technique. Our method proposes the use of standard raised cosine filter and square root raised cosine filter along with the AEXP companding process separately in DCT-SCFDMA system for different subcarrier mapping techniques e.g. interleaved frequency division multiple access and localized frequency division multiple access. Through extensive simulations, the numerical analysis presents that proposed architecture achieves significant improvements over the existing standard pulse shaping methods when used alone in DCT-SCFDMA system as far as the lowest PAPR is concerned. [ABSTRACT FROM AUTHOR]

For gated viewing systems with triangular and trapezoidal illuminating pulses, we have obtained the range-intensity profiles (RIPs) of the signal as the time delay was varied between the leading edges of the gate pulse and the illuminating pulse. We have established that if the duration of the illuminating pulse Δt is less than or equal to the duration of the gate pulse Δt, then the expressions for the characteristic distances are the same as for rectangular pulses and they can be used to determine the distance to objects. When Δt > Δt, in the case of triangular illuminating pulses the RIP is bell-shaped. For trapezoidal pulses, the RIP is bell-shaped with or without a plateau section. We propose an empirical method for determining the characteristic distances to the RIP maximum and the boundary points for the plateau section, which we then use to calculate the distance to the object. Using calibration constants, we propose a method for determining the distance to an object and we have experimentally confirmed the feasibility of this method. [ABSTRACT FROM AUTHOR]

The results of investigation into cesium hafnium chloride (Cs 2 HfCl 6 ) scintillating crystals as a promising detector to search for rare nuclear processes occurring in Hf isotopes is reported. The light output, quenching factor, and pulse-shape characteristics have been investigated at room temperature. The scintillation response of the crystal induced by α -particles and γ -quanta were studied to determine possibility of particle discrimination. Using the optimal filter method we obtained clear separation between signals with a factor of merit (FOM) = 9.3. This indicates that we are able to fully separate signals originating from α -particles and γ -quanta. Similar fruitful discrimination power was obtained by applying the mean time method (FOM = 7) and charge integration method (FOM = 7.5). The quenching factor for collimated 4 MeV α -particles is found to be 0.36, showing that α -particles generate more than a third of the light compared to γ -quanta at the same energy. [ABSTRACT FROM AUTHOR]

For valid results in split Hopkinson pressure bar testing, the strain history in the incident bar must be measured at a location where the incident and reflected waves do not overlap. This may prove problematic if the loading pulse is long relative to the length of the incident bar, e.g. due to pulse shaping or when long pressure bars are not available. In this paper an experimental technique for the elimination of overlapping stress waves is presented. By ensuring that the incident wave traverses the bar without noticeable dispersive oscillatory components, a complete pulse history free from superpositioning stress waves can be rapidly constructed via the collation of data from two sets of strain gauges attached at two locations on the incident bar. Experimentation on a sand specimen subsequently validated via finite element modeling demonstrates the advantage of this wave collation technique as it enables the use of longer loading pulses while still satisfying all necessary requirements pertinent to valid Hopkinson bar investigations. [ABSTRACT FROM AUTHOR]

We present design and analysis of an on-chip measurement infrastructure, which facilitates long-term monitoring of single-event transient durations in digital VLSI circuits exposed to uncontrollable radiation. Unlike the known oscilloscope-based methods, our approach is all-digital: SET durations are measured by the SET-gated counting of pulses generated by a high-frequency ring oscillator, and stored in an up/down-counter array organized in a ring. We carefully elaborate a comprehensive concept for making our infrastructure SEU tolerant, with the main challenge being to attain a sufficiently high probability of recording useful hits in the target before exhausting the SEU tolerance of the infrastructure. Our key contribution here concerns the protection of the counter array: Rather than resorting to radiation hardening or explicit triple modular redundancy (TMR), we save area by using a novel redundant duplex counter architecture: For a small number of recorded SETs, our architecture implicitly implements TMR, albeit in a way that degrades gracefully for larger numbers of recorded SETs. Besides standard functional and timing verification, we use Spice-based SET injection for verifying the effectiveness of our SEU-tolerant architecture, and some cross section-based probabilistic analysis for confirming that our measurement infrastructure based on it indeed achieves its purpose. [ABSTRACT FROM AUTHOR]

Expanded polystyrene concrete (flexible particles concrete) and alumina hollow ball concrete (rigid particles concrete) with volume content of 0%, 10%, 20%, 30%, 40% and 50% were prepared. In this paper, energy dissipation characteristics of different types of particles concrete were investigated, while the mechanism was analyzed. Impact compression experiments were carried out by a Ф100 mm split Hopkinson pressure bar (SHPB) apparatus which was improved by pulse shaping technique. Main conclusions are as follows: As for flexible particles concrete, the adding of flexible particles with volume content of 20% can effectively improve specific energy absorption and energy absorption of concrete, and the rigid particles concrete achieve the best energy absorption performance at the volume content of 40%. Through the analysis of fracture morphologies, the damage degree of the ordinary concrete and particles concrete increase as the incident energy change rate increases. The energy absorption performance of flexible particles concrete with volume content of 20% is better, compared with rigid particles concrete with volume content of 40%.Therefore, with volume content of 20%, the flexible particles concrete has characteristics of the most excellent energy dissipation and a wide development prospect in engineering application. [ABSTRACT FROM AUTHOR]

The FAZIA apparatus exploits Pulse Shape Analysis (PSA) to identify nuclear fragments stopped in the first layer of a Silicon-Silicon-CsI(Tl) detector telescope. In this work, for the first time, we show that the isotopes of fragments having atomic number as high as Z∼20 can be identified. Such a remarkable result has been obtained thanks to a careful construction of the Si detectors and to the use of low noise and high performance digitizing electronics. Moreover, optimized PSA algorithms are needed. This work deals with the choice of the best algorithm for PSA of current signals. A smoothing spline algorithm is demonstrated to give optimal results without requiring too much computational resources. [ABSTRACT FROM AUTHOR]

Since the baseline of the unipolar pulse shaper have the direct-current (DC) offset and drift, an additional baseline estimator is need to obtain baseline values in real-time. The bipolar zero-area (BZA) pulse shapers can be used for baseline restoration, but they cannot restrain the baseline drift due to their asymmetrical shape. In this study, three trapezoids are synthesized as a symmetrical zero-area (SZA) shape, which can remove the DC offset and restrain the baseline drift. This baseline restoration technique can be easily implemented in digital pulse processing (DPP) systems base on the recursive algorithm. To strengthen our approach, the iron's characteristic x-ray was detected using a Si-PIN diode detector. Compared with traditional trapezoidal pulse shapers, the SZA trapezoidal pulse shaper improved the energy resolution from 237 eV to 216 eV for the 6.403 keV Kα peak. [ABSTRACT FROM AUTHOR]

Microwave photonics is a prominent field in which photonic technologies are used to empower and extend the functionalities of microwave system which is a very tough exercise to fulfill directly in microwave domain. Focusing towards high power lasers to get a very short and intense pulse has forced to re-consider the possibilities of optical pulse compression at high energy. Pulse compression helps in generation of pulse of long duration and thus compress optical pulses to get the short pulse duration required for increasing the range-resolution of radar. A temporal pulse shaping approach for photonic generation of an arbitrary chirped microwave waveform with an increased time-bandwidth product (TBWP) is proposed and experimentally demonstrated in this paper. The main advantage of this proposed model is high time-bandwidth product (TBWP) in the range of 100-150 which leads to an increased range resolution of RADAR (Radio Detection and Ranging). [ABSTRACT FROM AUTHOR]

Optical frequency comb is an optical spectrum with equispaced frequency lines, used in different applications, for instance, in optical communications. In this application, when an optical spectrum is propagated in single-mode fiber, temperature fluctuations, normal dispersion, and mechanical vibrations can affect the peak power and phase of the comb lines. In consequence, compensation techniques are required to correct the spectral shape, distorted by non-flatness and phase shifts of the spectrum lines. In this research, a method for analyzing optical frequency comb behavior and the spectral shape in terms of phase and intensity is used. This approach is based on fuzzy cellular automata (FCA) to catch up the dynamic of spectrum behavior, fuzzy clustering methods to classify the measured data, and intuitionistic fuzzy entropy to validate the analysis. Two settings to generate optical frequency comb are considered in the experiments: two intensity Mach- Zehnder modulators and mode- locking laser (picosecond pulsed source). Both comb line spectra are propagated through 25 km of single- mode fiber. Using the pulse shaper at the optical link output, the spectrum is corrected in flatness and phase shift. The pulse shaper was controlled by a computer, where the proposed method was implemented as a control algorithm based on information obtained by the analysis results. In the experiment, inside the framework of FCA and intuitionistic fuzzy sets (IFSs), the evolution rules 27 (experiment 1) and 184 (experiment 2) were used to find the dynamic behavior of comb spectrum, chosen after a performance comparison with another evolution rules. The comparison was carried out through the calculation of mean and standard deviation of phase shift and power peak, periodicity of FCA, and computational cost. For the first experiment, the change of peak powers was reduced from 4.34 dBm to 1.78 dBm and the phase shift was minimized from − 0.2901 rad to − 0.2618 rad . Instead, the second experiment is observed a correction in flatness from 22.13 dBm to 19.89 dBm and the standard deviation of phase shift was reduced from 0.00067 rad to 0.000471 rad . [ABSTRACT FROM AUTHOR]

A silicon-efficient time-interleaved pulse-shrinking time-to-digital converter (TDC) is proposed. The proposed TDC consists of a 16-stage coarse pulse-shrinking TDC with constant per-stage shrinkage 4.8 ns and a pair of 16-stage fine pulse-shrinking TDCs operated in a time-interleaved manner with constant per-stage shrinkage 296 ps. A simple residual time extraction method is proposed to extract the residual pulse of the coarse TDC simultaneously with digitization carried out by the TDC so that the digitization can be carried out by both the coarse and fine TDCs simultaneously to minimize conversion time. The characteristics of the proposed TDC including silicon consumption, power consumption, conversion time, jitter, and mismatch-induced timing errors are investigated. The proposed TDC was implemented in an IBM 130 nm 1.2 V CMOS technology. Simulation results show that the TDC offers 0.296-76.8 ns dynamic range, 850 ps conversion time, 0.285 LSB differential nonlinearity, and 0.78 LSB integral nonlinearity while consuming 7 mW. [ABSTRACT FROM AUTHOR]

In this paper, we studied several key problems in the shock calibration of high-g accelerometers, in which the Hopkinson bar system was employed as the loading and testing device. Firstly, in order to generate a strain pulse (the excitation signal in shock calibration) with high amplitude and a wide frequency bandwidth, the pulse shaping techniques by adjusting the geometry of projectile were numerically investigated. It was found that a smaller degree of taper at the front end of the projectile causes lower amplitude and wider duration of the acceleration pulse. The findings in studying pulse shaping technique could guide the choice of the projectile's geometry in the dynamic linearity calibration of accelerometers. Second, a novel method of the dynamic linearity calibration for accelerometers was proposed and verified by experimental tests. In the calibration process, we employed a single-barrel gun instead of the double-barrel gun (proposed in earlier studies) to launch two coaxial cylindrical projectiles, such that the synchronous impact of the two projectiles can be easily achieved in practice. Lastly, the efficiency of this developed calibration method was discussed in details. The calibration system used in this study is able to achieve a testing range from thousands of g to nearly 300,000 g. [ABSTRACT FROM AUTHOR]

Spectrally contained OFDM-based waveforms are considered key enablers for a flexible air interface design to support a broad range of services and frequencies as envisaged for 5G mobile systems. By allowing for the flexible configuration of physical layer parameters in response to diverse requirements, these waveforms enable the in-band coexistence of different services. One candidate from this category of waveforms is pulse-shaped OFDM, which follows the idea of subcarrier filtering while fully maintaining the compatibility with CP-OFDM. In this paper, we provide an overview of pulse shaping methods in OFDM systems and propose a new pulse-shaped design method with arbitrary length constraint and good time-frequency localization property. Based on the pulse design, we discuss different receiver realizations and present a criterion for pulse shape evaluation. In addition, the parameterizations of OFDM system to address diverse requirements of the services envisaged for the 5G systems are described. Link and system performance results for selected scenarios show that a proper design of the OFDM numerologies and pulse shapes could substantially improve the performance under time and frequency distortions. Furthermore, pulse-shaped OFDM is able to support asynchronous transmissions and reduce the signal sensitivity to Doppler distortions, rendering it beneficial for various applications from the context of vehicular communications and the Internet-of-things. [ABSTRACT FROM AUTHOR]

The Movable 37 Ar Rapid Detection System (MARDS) was developed by the Institute of Nuclear Physics and Chemistry of the China Academy of Engineering Physics in 2006 for on-site inspections under the Comprehensive Test Ban Treaty. It is a small and portable system that can quickly acquire data at suspected nuclear test sites. In this work, digital pulse shape discrimination (PSD) was used to process data from test samples to reduce electronic noise. The experimental results demonstrate that PSD combined with principal component analysis can classify and reject many noise sources. Thus, the threshold for the signal can be set low, expanding MARDS valid data acquisition capability, especially in very low-level and low-energy counting situations. [ABSTRACT FROM AUTHOR]

An algorithm is proposed that provides reliable discrimination between neutrons and γ rays in mixed fields and reduces the influence of γ-ray pileups at a slight complication of the hardware and the algorithms. The algorithm uses a stepwise Gatti filter for two detection periods (a short period of several hundreds of nanoseconds and a long period of a few microseconds) for the same event. Using mathematical simulation of 12000 neutron and γ-ray events, it has been demonstrated that at particle energies of ~128 keV in the electron equivalent ( ee), the algorithm suppresses γ-ray pileups on a level of 10 with a neutron loss of only approximately 1%. Due to the proposed algorithm, the counting ability is of the order of 10 events/s. [ABSTRACT FROM AUTHOR]

A large diameter Hopkinson tube has been developed to measure the dynamic fracture toughness of materials. The stress wave propagation behavior in the Hopkinson tube under different impact conditions were studied both experimentally and numerically. Both the experimental and simulated results indicated that the characteristics of the incident stress pulse critically depended on the impact alignment conditions. When the striker tube impacts the incident tube in an axial, normal alignment condition, the incident pulse shows an obvious dispersive effect. While under an oblique impact condition, a smooth incident pulse with a long rise time is achieved. Therefore, an oblique impact pulse shaping technique is proposed in this study. [ABSTRACT FROM AUTHOR]

Serious pulse temporal overlap in amplifiers would result in the decrease of energy extraction efficiency and the increase of pulse-shape distortion (PSD). Precisely predicting pulse temporal overlap is of significance to an effective amplifier design. In this work, the analytical expressions with complete pulse overlap are derived and a numerical method is proposed to solve the case with partial temporal overlap for a double-pass Nd:YAG amplifier. Our studies, in which pulse temporal overlap is taken into account, can precisely predict the output energy and temporal shape, compared to the results from Hirano and other experiments. In addition, our numerical routes could provide the applicable range of analytical solutions to conventional Frantz–Nodvik equations in the case of pulse overlap, further extending the applicability and reducing computational costs. For given conditions, energy reduction and PSD are mainly determined by the overlap degree. For step-shaped pulse, we demonstrate that avoiding overlap in the peak pulse and allowing overlap in the foot pulse have small impacts on the energy extraction and PSD, which extends the range of duration of the pulse for a designed amplifier. Our investigations might provide an efficient way to carefully design a pulsed amplifier with controllable temporal overlap. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Randomly oriented HOD molecules are vibrationally excited via the dynamic Stark effect. • Simple linear temporal chirp of a UV pulse can control the selectivity of bond breaking in HOD. • In order to narrow the gap between theory and experiment, the feasibility of the proposed control scheme is emphasized. Abstract The VUV photodissociation dynamics of HOD in the first ( A ∼ -state) absorption band following a non-resonant impulsive vibrational excitation is studied theoretically. We show that a change in the linear temporal chirp of a VUV pulse with a fixed frequency distribution leads to control of the branching ratio (H + OD)/(D + OH) between the two fragmentation channels. [ABSTRACT FROM AUTHOR]

Single crystals of Gd 3 Ga 3 Al 2 O 12 :Ce,B and CsI:Tl were grown by Czochralski and Bridgman techniques, respectively. While both the crystals exhibited similar emission at about 550 nm, their scintillation decay times showed significantly different characteristics. The average scintillation decay time of Gd 3 Ga 3 Al 2 O 12 :Ce,B crystal was found to be about 284 ns for alpha excitation compared to 108 ns measured for a gamma source. On the other hand in CsI:Tl crystals, the alpha excitation resulted in a lower average decay time of 600 ns compared to 1200 ns with gamma excitation. Their pulse shape discrimination (PSD) for gamma and alpha radiations were studied by coupling the scintillators with photomultiplier tube or SiPM and employing an advanced digitizer as well as a conventional zero-crossing setup. In spite of having a poor α/γ light yield ratio, the PSD figure of merit and the difference of zero-crossing time in Gd 3 Ga 3 Al 2 O 12 :Ce,B crystals were found to be superior in comparison to CsI:Tl crystals. [ABSTRACT FROM AUTHOR]

The increasing use of backscatter radio for pervasive Internet-of-Things systems as a low-power and low-cost communication scheme will result in dense deployments of tags that need to operate under bandwidth (BW) constraints. Typical backscatter tags and computational radio frequency (RF) identification systems are unnecessarily limited to modulating data with “ON–OFF” switching front-ends, which leads to extensive spectrum occupancy, due to the rectangular pulses. This paper sets the foundations to overcome these limitations and proposes designs of RF front-ends that are capable of varying the tag reflection coefficient in a continuous way over time. Arbitrary waveforms can be generated to perform pulse shaping on the backscattered signals, which require significantly reduced BW. The principles presented in this paper will enable sophisticated tags to perform complex modulation schemes under BW constraints, while maintaining a very low RF front-end complexity, using a single nonlinear component such as a p-i-n diode or field-effect transistor. Migrating the idea of pulse shaping from complex power-demanding active radios to such minimal RF front-ends will complete backscatter radio as a communication scheme for simple RF tags and sensors in large-scale deployments. Each tag becomes a miniature software-defined radio that implements diverse communication schemes with increased spectral efficiency. [ABSTRACT FROM PUBLISHER]

In any neutron scattering experiment the measurement of the position of the scattered neutrons and their respective velocities is necessary. In order to do so, a position sensitive detector as well as a way to determine the velocities is needed. Measuring the velocities can either be done by using only a single wavelength and therefore velocity or by creating pulses, where the start and end time of each pulse is known and registering the time of arrival at the detector, which is the case we want to consider here. This pulse shaping process in neutron scattering instruments is usually done by using a configuration of several choppers. This set of choppers is then used to define both the beginning and the end of the pulse. Additionally there is of course also a selection in phase space determining the final resolution that can be achieved by the instrument. Taking into account the special requirements of a specific instrument, here a small-angle neutron scattering instrument, creates an additional set of restrictions that have to be taken into account. In this manuscript a chopper configuration for two possible settings, namely a maximum flux and a high-resolution mode will be presented. [ABSTRACT FROM AUTHOR]

In the context of gridless optical multicarrier systems, we propose a method for intercarrier interference (ICI) mitigation which allows bit error correction in scenarios of nonspectral flatness between the subcarriers composing the multicarrier system and sub-Nyquist carrier spacing. We propose a hybrid ICI mitigation technique which exploits the advantages of signal equalization at both levels: the physical level for any digital and analog pulse shaping, and the bit-data level and its ability to incorporate advanced correcting codes. The concatenation of these two complementary techniques consists of a nondata-aided equalizer applied to each optical subcarrier, and a hard-decision forward error correction applied to the sequence of bits distributed along the optical subcarriers regardless of prior subchannel quality assessment as performed in orthogonal frequencydivision multiplexing modulations for the implementation of the bit-loading technique. The impact of the ICI is systematically evaluated in terms of bit-error-rate as a function of the carrier frequency spacing and the roll-off factor of the digital pulse-shaping filter for a simulated 3 × 32-Gbaud single-polarization quadrature phase shift keying Nyquist-wavelength division multiplexing system. After the ICI mitigation, a back-to-back error-free decoding was obtained for sub-Nyquist carrier spacings of 28.5 and 30 GHz and roll-off values of 0.1 and 0.4, respectively. [ABSTRACT FROM AUTHOR]

The new generation of nuclear physics detectors that used to study nuclear reactions is considering the use of digital pulse shape analysis techniques (DPSA) to obtain the (A,Z) values of the reaction products impinging in solid state detectors. This technique can be an important tool for selecting the relevant reaction channels at the HYDE (HYbrid DEtector ball array) silicon array foreseen for the Low Energy Branch of the FAIR facility (Darmstadt, Germany). In this work we study the feasibility of using artificial neural networks (ANNs) for particle identification with silicon detectors. Multilayer Perceptron networks were trained and tested with recent experimental data, showing excellent identification capabilities with signals of several isotopes ranging from 12 C up to 84 Kr, yielding higher discrimination rates than any other previously reported. [ABSTRACT FROM AUTHOR]

Three algorithms were investigated for discriminating between neutrons and gamma rays in a pressurized 4 He gas fast neutron detector: charge comparison, weighted integration, and neutron-gamma model analysis (NGMA). For each algorithm, a comprehensive pulse shape discrimination study was conducted using time-of-flight measurements, receiver operator characteristic curves, figure of merit performance measures, and a comparison of performance between 252 Cf and PuBe mixed neutron/gamma sources. The NGMA method was found to have the best overall performance by both the figure of merit and the receiver operator characteristic curve. The results also illustrated the high gamma rejection efficiency of these detectors, which is desirable in a variety of neutron monitoring applications. [ABSTRACT FROM AUTHOR]

Pulse shaping techniques are discussed in this paper for the practicability of a developed high-g shock tester. The tester is based on collision principle where there is a one-level velocity amplifier. A theoretical and experimental study of pulse shaping techniques is presented. A model was built and theoretical formulae were deduced for the shock peak acceleration and its duration. Then theoretical analysis and some experiments were conducted. The test results verify the validity of theoretical model and show that the shock tester can generate the expected high-g shock pulses by integrated usage of different impact velocities and pulse shapers made from different materials. This is important in practical applications where the items under test can be shown to excite specific resonances at predetermined acceleration levels using the shock tester. [ABSTRACT FROM AUTHOR]

Investigation of subthermonuclear plasma confinement and heating in magnetic fusion devices such as GOL–3 and GDT at the Budker Institute (Novosibirsk, Russia) requires sophisticated equipment for neutron-, gamma- diagnostics and upgrading data acquisition systems with online data processing. Measurement of fast neutron flux with stilbene scintillation detectors raised the problem of discrimination of the neutrons ( n ) from background cosmic particles (muons) and neutron-induced gamma rays ( γ ). This paper describes a fast neutron flux analyzer with real-time digital pulse-shape discrimination (DPSD) algorithm FPGA-implemented for the GOL–3 and GDT devices. This analyzer was tested and calibrated with the help of 137 Cs and 252 Cf radiation sources. The Figures of Merit (FOM) calculated for different energy cuts are presented. [ABSTRACT FROM AUTHOR]

In this paper, Helmholtz equation for large core tapered fiber has been solved by using beam propagation method. The evolution of Gaussian input field, electric field and electric power at different linear tapering length have been studied. As an importance of adiabatic optical field transmission along tapered length, minimum tapering length has been obtained for this great task. Also, because of importance of transverse electric field distribution at the output of the tapered segment, the minimum tapering length for this purpose has been obtained. [ABSTRACT FROM AUTHOR]

Sensitivity to frequency offset in orthogonal frequency division multiplexing (OFDM)-based systems allow unwanted interference among the subcarriers, which results in intercarrier interference (ICI). A novel family of Nyquist-I pulses, named dual sinc pulses (DSPs), is proposed herein having three new design parameters, giving additional degrees of freedom to minimize ICI power in OFDM-based systems. Several Nyquist-I pulses have been studied and implemented to deal with the problem of frequency offset in OFDM-based systems. In this paper, we investigate the performance of DSPs in terms of ICI power, signal-to-interference power ratio (SIR), and bit error rate (BER) in OFDM-based systems. The frequency responses of the DSPs are studied by adjusting the values of the new design parameters. Theoretical and simulation results presented herein show that DSPs outperform other existing pulses in OFDM-based systems, in terms of ICI power, SIR power, and BER. [ABSTRACT FROM AUTHOR]