Systematic evaluation of a holmium:yttrium-aluminum-garnet laser lithotripsy device with variable pulse peak power and pulse duration

Objective:The Holmium:yttrium-aluminum-garnet(Ho:YAG)laser is the standard lithotrite for ureteroscopy.This paper is to evaluate a Ho:YAG laser with a novel effect function in vitro,which allows a real-time variation of pulse duration and pulse peak power.Methods:Two types of phantom calculi with four degrees of hardness were made for fragmentation and retropulsion experiments.Fragmentation was analysed at 5(0.5 J/10 Hz),10(1 J/10 Hz),and 20(2 J/10 Hz)W in non-floating phantom calculi,retropulsion in an ureteral model at 10(1 J/10 Hz)and 20(2 J/10 Hz)W using floating phantom calculi.The effect function was set to 25%,50%,75%,and 100%of the maximum possible effect function at each power setting.Primary outcomes:fragmentation(mm^3),the distance of retropulsion(cm);
5 measurements for each trial.Results:An increase of the effect feature(25%vs.100%),i.e.,an increase of pulse peak power and decrease of pulse duration,improved Ho:YAG laser fragmentation.This effect was remarkable in soft stone composition,while there was a trend for improved fragmentation with an increase of the effect feature in hard stone composition.Retropulsion increased with increasing effect function,independently of stone composition.The major limitations of the study are the use of artificial stones and the in vitro setup.Conclusion:Changes in pulse duration and pulse peak power may lead to improved stone fragmentation,most prominently in soft stones,but also lead to increased retropulsion.This new effect function may enhance Ho:YAG laser fragmentation when maximum power output is limited or retropulsion is excluded.

Peak Power Effect on Skin Rejuvenation Using IPL: Lumecca IPL Evaluation

A high peak power IPL system (Lumecca) was tested to determine the correlation between a high peak power and the successful treatment of pigmented and vascular lesions. Short pulse duration in the millisecond range and high peak power of 3.3 kW/cm2 enabled selective and effective destruction, not only of pigment, but also of vessels in a comparable manner to a pulsed dye laser. Only one treatment session at a low fluence (8 - 16 J/cm2) was sufficient to achieve the desired results.

Effect of Peak Power and Pulse Width on Coherent Doppler Wind Lidar’s SNR

The laser device is the core component of coherent Doppler wind lidar.The peak power and pulse width of laser transmitting pulse have important effects on SNR.Based on coherent Doppler wind pulse lidar,the peak power and pulse width influence on SNR is studied on the theoretical derivation and analysis,and the results show that the higher the peak power can realize the greater the signal-to-noise ratio of coherent Doppler wind lidar.But when the peak power is too large,the laser pulse may appear nonlinear phenomenon,which cause the damage of the laser.So,the peak power must be less than the stimulated brillouin scattering power threshold.Increasing the pulse width can make the laser device to output more energy,but it will also make the spatial resolution lower,and the influence of turbulence on SNR will be greater.After a series of simulation analyses,it can be concluded that when the peak power is 650W and the pulse width is 340ns,the SNR of the system can be maximized.In addition,the coherent Doppler wind lidar system is set up to carry out corresponding experimental verification.The experimental results are consistent with the theoretical analysis and simulation,which verifies the correctness of the theoretical analysis and simulation results.It provides theoretical basis and practical ex-perience for the design of laser transmitting pulse in coherent Doppler wind lidar system.

Test Analysis of Traction Battery Peak Power

The test process of electric vehicles (EVs) traction battery peak power is analyzed in detail. Aimed at a special “traction” design of versatile battery—HORIZON~ C^2M Battery, the features are introduced. According to the peak power test schedule, the test parameters of HORIZON~ C^2M Battery are calculated and the charging and discharging experiments are carried out. The sustained (30 s) discharge power capability of battery at 2/3 of its open circuit voltage at each of various depths of discharge is determined. The dynamic internal resistance under peak power test is established. Considering the temperature impact during discharging, the peak power capability at each of various depths of discharge is corrected. The correctness of peak power test is validated by combining theory analysis with test results.

High Peak Power, Single-polarized, Sub-nanoseconds Pulses Generation of a Yb-doped Rod-type Photonic Crystal Fiber Amplifier

We report a high-peak-power, single-polarized master oscillator power amplification system employing polarization- maintaining Yb-doped rod-type photonic crystal fiber. The MOPA system comprises of a Q-switched microchip laser generating ~630ps pulses at 8.6 kHz repetition-rate and two amplification stages employing double cladding fiber and rod-type PCF respectively. The MOPA system obtains narrow spectral bandwidth, single-polarized pulses of 9W maximum output average power, corresponding to peak power of 1.7MW.

Assessment of Axial Power Peaking Factors in GHARR-1 LEU Core: A Decadal Simulation Analysis

This study aims to thoroughly investigate the axial power peaking factors (PPF) within the low-enriched uranium (LEU) core of the Ghana Research Reactor-1 (GHARR-1). This study uses advanced simulation tools, like the MCNPX code for analysing neutron behavior and the PARET/ANL code for understanding power variations, to get a clearer picture of the reactor’s performance. The analysis covers the initial six years of GHARR-1’s operation and includes projections for its whole 60-year lifespan. We closely observed the patterns of both the highest and average PPFs at 21 axial nodes, with measurements taken every ten years. The findings of this study reveal important patterns in power distribution within the core, which are essential for improving the safety regulations and fuel management techniques of the reactor. We provide a meticulous approach, extensive data, and an analysis of the findings, highlighting the significance of continuous monitoring and analysis for proactive management of nuclear reactors. The findings of this study not only enhance our comprehension of nuclear reactor safety but also carry significant ramifications for sustainable energy progress in Ghana and the wider global context. Nuclear engineering is essential in tackling global concerns, such as the demand for clean and dependable energy sources. Research on optimising nuclear reactors, particularly in terms of safety and efficiency, is crucial for the ongoing advancement and acceptance of nuclear energy.

Microstructure and mechanical properties of Cr films deposited with different peak powers by high-power impulse magnetron sputtering

For high-power impulse magnetron sputtering(HIPIMS),the peak power applied to the target is of great importance for regulating the ionization degree of the metal target and ion/atom flux ratio.In this work,chromium(Cr)films were deposited on 316-L stainless steel substrates and silicon(100) wafers with different peak powers by HIPIMS.The relationship between peak target power and properties of Cr films was explored in detail.The resulting structure and mechanical properties of deposited Cr films were characterized by X-ray diffraction(XRD),transmission electron microscope(TEM),atomic force microscopy(AFM),indentation hardness and scratch tester.The results indicate that the ionization degree of metal target and ion/atom flux ratio increase with the increase in peak power but without the loss of deposition rate at the same time.At low ionization degree,the deposited Cr film has low compressive residual stress and low hardness but good adhesion strength.When the ionization degree of target metal increases with increasing peak power,Cr film exhibits finer size and smoother surface with improved hardness but decreased adhesion strength.

A novel reconfiguration of the solar array to enhance peak power and efficiency under partial shading conditions:experimental validation

Non-homogeneous irradiation patterns and temperature levels immensely affect the performance of solar photovoltaic arrays.Partial shading conditions on solar arrays reduce the peak power and efficiency.This paper provides a new remedy called a novel Ramanujan reconfiguration(NRR)to eliminate this physical shading problem in solar photovoltaic systems.NRR is a static-based reconfigured technique that is built using a three-diode model with the help of the MATLAB®/Simulink®tool.The special feature of the proposed NRR technique is that when shade occurs on the solar modules,it gets realigned in a particular row,column,diagonal,corner,centre and middle peripheral cages.This helps over a wide range of shade dispersion on the solar array.The novel topology is tested against the conventional total cross-tied(TCT)model and recently introduced advanced reconfigured models,namely odd–even topology(OET)and Kendoku topology(KDT).The results are tested under certain shading conditions.The proposed NRR technique increases the peak power by 4.45,2.15 and 2.17 W under the first shading condition regarding TCT,OET and KDT.Its efficiency is improved by 0.51–2.18%under the third shading condition compared with other considered models in this study.In addition,NRR leads to smooth output curves under the second,third and fourth shading conditions,effectively mitigating the local power peaks.The experimental results show the proposed enhanced performance of the novel model against the other models.Graphical Abstract Remedy for physical problem correlated with solar photovoltaics Comparison with traditional and recent solar models Conclusion:NRR has effectively handled the problem related with solar models.It has improved the efficiency up to 31.44%under S4.Also,smooth output curves under S2-S4 shows its effectiveness in mitigating the local power peaks.Greater power gain at 3.94%under S4 is achieved by novel model.Real-time verification proves the supremacy of novel proposed model over other considered models in this work.

PSO-DBNet for Peak-to-Average Power Ratio Reduction Using Deep Belief Network

Data transmission through a wireless network has faced various signal problems in the past decades.The orthogonal frequency division multiplexing(OFDM)technique is widely accepted in multiple data transfer patterns at various frequency bands.A recent wireless communication network uses OFDM in longterm evolution(LTE)and 5G,among others.The main problem faced by 5G wireless OFDM is distortion of transmission signals in the network.This transmission loss is called peak-to-average power ratio(PAPR).This wireless signal distortion can be reduced using various techniques.This study uses machine learning-based algorithm to solve the problem of PAPR in 5G wireless communication.Partial transmit sequence(PTS)helps in the fast transfer of data in wireless LTE.PTS is merged with deep belief neural network(DBNet)for the efficient processing of signals in wireless 5G networks.Result indicates that the proposed system outperforms other existing techniques.Therefore,PAPR reduction in OFDM by DBNet is optimized with the help of an evolutionary algorithm called particle swarm optimization.Hence,the specified design supports in improving the proposed PAPR reduction architecture.

Pulsed LD side-pumped MgO：LN electro-optic cavity-dumped 1123 nm Nd： YAG laser with short pulse width and high peak power

We report a cavity-dumped 1123 nm laser with narrow pulse width and high peak power by an Mg O: LN crystal electrooptic(EO) modulator. Based on the structural optimization design of a folded biconcave cavity using the 808 nm pulsed laser diode(LD) side-pumped ceramic Nd: YAG rod, output pulses with maximum pulse energy and peak power up to39.6 m J and 9.73 MW were obtained, corresponding to 100 Hz repetition rate and 4.07 ns pulse width. The instabilities of pulse width and pulse energy were ±1.55% and ±2.06%, respectively. At the highest repetition rate of 1 kHz, the pulse energy, pulse width, and peak power were 11.3 mJ, 5.05 ns, and 2.24 MW, respectively. The instabilities of pulse width and pulse energy were ±2.65% and ±3.47%, respectively.

High peak power subnanosecond pulse characteristics with different wall structured CNTs in a doubly QML Nd:Lu_(0.15)Y_(0.85)VO_4 laser

By simultaneously employing both an electro-optic modulator and carbon nanotube saturable absorber(CNT-SA)in a dual-loss modulator, a subnanosecond single mode-locking pulse underneath a Q-switched envelope with high peak power was generated from a doubly Q-switched and mode-locked(QML) Nd:Lu_(0.15)Y_(0.85)VO_4 laser at1.06 μm for the first time, to our knowledge. CNTs with different wall structures—single-walled CNTs(SWCNTs),double-walled CNTs(DWCNTs), and multi-walled CNTs(MWCNTs)—were used as SAs in the experiment to investigate the single mode-locking pulse characteristics. At pump power of 10.72 W, the maximum peak power of1.312 MW was obtained with the DWCNT.

Study and development of high peak power short pulse Nd:YAG laser for peening applications

Because short pulse Nd:YAG laser of nanosecond pulse-width and high peak power has a unique capability to improve the mechanical properties of metal parts,a study on the development of high peak power short pulse from Nd:YAG laser along with its peening application has been performed.The design scheme of laser and the characteristic of laser beam transmission are presented and discussed.A pulse energy of 25 J with 15 ns pulse-width and a maximum peak power of 1660 k W laser system which use one oscillation and eight amplifiers has been achieved.Laser beam has a max divergence angle of 0.03 mrad,a pulse-to-pulse pulse-width stability of±0.1 ns,and the pulse-to-pulse energy stability factors of less than±2.8%.A low value of divergence means an easier modification of a nearly hat-top laser beam intensity profile and an easier transmission of laser beam.To evaluate the performance of the laser system,several metal materials are processed.Laser peening quality and efficiency are analyzed by using an optical microscope,a transmission electron microscope,and an X-ray diffraction device.The processing results show that the performance of this laser system is excellent.

Estimate of China's energy carbon emissions peak and analysis on electric power carbon emissions

China's energy carbon emissions are projected to peak in 2030 with approximately 110%of its 2020 level under the following conditions:1)China's gross primary energy consumption is 5 Gtce in 2020 and 6 Gtce in 2030;2)coal's share of the energy consumption is 61%in 2020 and55%in 2030;3)non-fossil energy's share increases from 15%in 2020 to 20%in 2030;4)through 2030,China's GDP grows at an average annual rate of 6%;5)the annual energy consumption elasticity coefficient is 0.30 in average;and 6)the annual growth rate of energy consumption steadily reduces to within 1%.China's electricity generating capacity would be 1,990 GW,with 8,600 TW h of power generation output in 2020.Of that output 66%would be from coal,5%from gas,and 29%from non-fossil energy.By 2030,electricity generating capacity would reach3,170 GW with 11,900 TW h of power generation output.Of that output,56%would be from coal,6%from gas,and 37%from non-fossil energy.From 2020 to 2030,CO2emissions from electric power would relatively fall by 0.2 Gt due to lower coal consumption,and relatively fall by nearly 0.3 Gt with the installation of more coal-fired cogeneration units.During 2020e2030,the portion of carbon emissions from electric power in China's energy consumption is projected to increase by 3.4 percentage points.Although the carbon emissions from electric power would keep increasing to 118%of the 2020 level in 2030,the electric power industry would continue to play a decisive role in achieving the goal of increase in non-fossil energy use.This study proposes countermeasures and recommendations to control carbon emissions peak,including energy system optimization,green-coal-fired electricity generation,and demand side management.

REDUCING THE PEAK-TO-AVERAGE POWER RATIO OF OFDM SYSTEM WITH LOW COMPLEXITY

This paper proposes a companding scheme, where small signals are enlarged and large signals are reduced, to reduce the Peak-to-Average Power Ratio(PAPR). Computer simulation results show that the proposed technique has two advantages at least when compared with the conventional methods such as partial transmit sequence, selective mapping and the previous companding. First, it gets better PAPR performances with a lower complexity. Second, the scheme achieves greater performances gain with hardly any damnification of OFDM signals in some degree.

A Novel Peak-to-Average Power Ratio Reduction Scheme via Tone Reservation in OFDM Systems

In this paper, a novel signal-to-clipping noise ratio and least squares approximation tone reservation scheme(SCR-LSA TR) is proposed to reduce the peak-to-average power ratio for orthogonal frequency division multiplexing systems. During the SCR procedure, only the element with the maximal amplitude is picked for processing, which not only decreases the algorithm complexity, but also helps to overcome the BER deterioration. With the LSA method, the amplitude of the peak-cancelling signals can approximate to that of the original clipping noise as much as possible. Through the combination of the optimization factor in the LSA method, the classic SCR method can achieve better PAPR reduction with faster convergence. Simulation results show that the proposed SCR-LSA TR scheme has less in-band distortion and smaller out-of-band spectral radiation. The BER of the proposed scheme shows a better performance especially under the 16-QAM over the additive white Gaussian noise channel.

Frequency offset estimation based on peak power ratio in LTE system

Orthogonal frequency division multiplexing(OFDM)is one of the key techniques for long term evolution(LTE)system.Frequency offset estimation of OFDM is an essential issue.Especially in the high-speed environment,the frequency offset will become large.Based on the features of LTE uplink physical random access channel(PRACH),this paper proposes a new frequency offset algorithm by using peak power ratio to enlarge the range of frequency offset estimation.According to the relation between frequency offset and the power delay profile(PDP),the ratio of the peak power of the PDP at the main window to that at the negative window or positive window is utilized to estimate frequency offset.Simulation results show that the new proposed algorithm extends the estimation range of frequency offset from 1 000 Hz to 1 250 Hz.Meanwhile the accuracy of frequency offset estimation is almost not lost.Particularly in low signal noise ratio(SNR),the new algorithm has lower mean square error(MSE)compared with traditional phase differential algorithm.

Cryogenic nanosecond and picosecond high average and peak power(HAPP) pump lasers for ultrafast applications

Using cryogenic laser technology, it is now possible to design and demonstrate lasers that have concomitant high average and peak powers, with near-diffraction-limited beam quality. We refer to these new laser systems as HAPP lasers. In this paper, we review important laser crystal materials properties at cryogenic temperature, with an emphasis on Yb lasers, and discuss the important design considerations, including the laser-induced damage threshold, nonlinear effects and thermal effects. A comprehensive model is presented to describe diode pulsed pumping with arbitrary duration and repetition rate, and is used with the Frantz–Nodvik equation to describe, to first order, the performance of HAPP laser systems. A computer code with representative results is also described.

Design and Application of Wind Power Peak Control Technology

Wind power control technology is an important part of intelligent control in wind farms. By the automatic calculation and implementation of control strategy, problems such as imprecise of manual control scheduling, slow adjust rate, heavy workload, etc. have been solved. It can improve the capacity of wind power grid, and it also has the important meaning to the safe and stable operation of power grid. This paper introduces wind power control system from certain aspects such as control mode, control principle, and so on.