Minimum Delay Time Research Articles

Pre-Emphasis Pulse Design for Reducing Bit-Line Access Time in NAND Flash Memory

This paper describes pre-emphasis (PE) pulses to reduce bit-line (BL) access time in NAND flash memory. Optimum PE pulse widths and resultant minimum BL delay times are investigated, where the BL delay is determined by the sense current at the input terminal of a sensing circuit in contrast with the word-line (WL) delay that is determined by the WL voltage at the gate of a selected memory cell. Two BL models are used, namely, a single-line model (SLM) for the shielded BL read operation and a three-line model (TLM) for the all-BL read operation. Under the condition that the sense current delay is defined by the time when the sense current becomes stable between 110% and 90% of the cell current and the BL voltage delay is defined by the time when the BL voltage at the selected cell reaches a window between 110% and 90%, SPICE simulation results show that the sensed current delay and the BL voltage delay are reduced by 43% and 36% in the case of SLM and by 16% and 28% in the case of TLM, respectively. Thus, the key results are the following: (1) PE pulses are effective to reduce the sense current delay time for BL access, as well as the BL voltage delay time for both SLM and TLM; (2) the sensitivity of the PE pulse on the delay time is much larger for the sensed current delay than the BL voltage delay due to the absence of filtering with the RC delay element in BL delay; and (3) address-dependent PE pulse control can reduce the sense current delay significantly, especially for access to cells closely located to the sensing circuit.

Toward high all-optical data writing rates in synthetic ferrimagnets

Although all-optical magnetization switching with fs laser pulses has garnered much technological interest, the ultimate data rates achievable have scarcely been investigated. Recently, it has been shown that after a switching event in a GdCo alloy, a second laser pulse arriving 7 ps later can consistently switch the magnetization. However, it is as of yet unknown whether the same holds in layered ferrimagnetic systems, which hold much promise for applications. In this work, we investigate the minimum time delay required between two subsequent switching events in synthetic ferrimagnetic Co/Gd bilayers using two fs laser pulses. We experimentally demonstrate that the minimum time delay needed for consistent switching can be as low as 10 ps. Moreover, we demonstrate the importance of engineering heat diffusion away from the magnetic material as well as control over the laser pulse energy. This behavior is reproduced using modeling, where we find that the second switch can occur even when the magnetization is not fully recovered. We further confirm that heat diffusion is a critical factor in reducing the time delay for the second switch, while also confirming a critical dependence on laser energy.

Optimal design of proportional integral derivative acceleration controller for higher‐order nonlinear time delay system using m‐MBOA technique

AbstractIn general, the parameter adjustment is used to design the proportional‐integral‐derivative (PID) controllers. Despite that, to enhance the capacity of control performance by adjusting parameters is limited. Therefore, in this paper, an optimal design of proportional integral derivative acceleration (PIDA) controller is proposed for higher‐order nonlinear time delay system (TDS) using modified butterfly optimization algorithm (MBOA) with the aim of achieving optimal closed‐loop response, which is enhanced with mutualism system (m‐MBOA). In the proposed approach, the mutualism stage of symbiotic organisms search (SOS) and butterfly optimization algorithm (BOA) global exploration phase is considered. The major aim of the proposed approach is to “tune the gain of the PIDA controller to get the desired response.” It reduces the drawback of the PIDA controller in the higher‐order TDS using advanced control limits is the individuality of the proposed approach. Here, the proposed approach is employed to reduce the higher‐order delays together with reliability limits, like minor overshoots, time resolution, and fixed stage deficiency. To evaluate the proposed PIDA controller, the execution is done by the MATLAB/Simulink platform, also its efficiency is compared with existing approaches. Moreover, the proposed and existing approaches are analyzed with mean, median, and standard deviations. From the analysis, the proposed approach achieves the stability with minimal delay time and reduces the computational complexity. Finally, the simulation results demonstrate that the proposed approach can efficiently with accurately find the optimal global solutions.

Review Paper on LoRa based technologies for Vehicular and Tracking applications

Abstract: LoRa stands For Long Range. It is a low powered wide area network derived from chirp spread spectrum technology and encodes information through chirp pulses on to the radio waves. The range of LoRa greatly varies from few meters to approximately 100 Kilometers depending on the mode of operation. The main advantage of LoRa against Bluetooth, WiFi and ZigBee is its long range and it is well suited for transmission of small chunks of data with low bit rates. LoRa is generally operated at 915MHz, 868MHz and 433MHz which are Sub-Giga Heartz bands. These are a part of the ISM bands which are reserved for Industrial and Medical Purposes Internationally which are free of cost and do not require any kind of licensing. Vehicular communication is a form of exchanging messages between various vehicular and roadside units regarding their location, speed and much more. The LoRa technology when integrated with Vehicular Communication establishment of green corridors for Emergency vehicles by clearing the traffic and help in reaching the destination with minimal time delay. Keywords: LoRa, ISM Bands, Vehicular Communication

Predation risk can modify the foraging behaviour of frugivorous carnivores: Implications of rewilding apex predators for plant-animal mutualisms.

Apex predators play key roles in food webs and their recovery can trigger trophic cascades in some ecosystems. Intra‐guild competition can reduce the abundances of smaller predators and perceived predation risk can alter their foraging behaviour thereby limiting seed dispersal by frugivorous carnivores. However, little is known about how plant–frugivore mutualisms could be disturbed in the presence of larger predators.We evaluated the top‐down effect of the regional superpredator, the Iberian lynx Lynx pardinus, on the number of visits and fruits consumed by medium‐sized frugivorous carnivores, as well as the foraging behaviour of identified individuals, by examining the consumption likelihood and the foraging time.We carried out a field experiment in which we placed Iberian pear Pyrus bourgaeana fruits beneath fruiting trees and monitored pear removal by frugivorous carnivores, both inside and outside lynx ranges. Using camera traps, we recorded the presence of the red fox Vulpes vulpes, the Eurasian badger Meles meles and the stone marten Martes foina, as well as the number of fruits they consumed and their time spent foraging.Red fox was the most frequent fruit consumer carnivore. We found there were fewer visits and less fruit consumed by foxes inside lynx ranges, but lynx presence did not seem to affect badgers. We did not observe any stone marten visits inside lynx territories. The foraging behaviour of red foxes was also altered inside lynx ranges whereby foxes were less efficient, consuming less fruit per unit of time and having shorter visits. Local availability of fruit resources, forest coverage and individual personality also were important variables to understand visitation and foraging in a landscape of fear.Our results show a potential trophic cascade from apex predators to primary producers. The presence of lynx can reduce frugivorous carnivore numbers and induce shifts in their feeding behaviour that may modify the seed dispersal patterns with likely consequences for the demography of many fleshy‐fruited plant species. We conclude that knowledge of the ecological interactions making up trophic webs is an asset to design effective conservation strategies, particularly in rewilding programs.

High energy density renewable fuels based on multicyclic sesquiterpene: Synthesis and performance

Considering the global carbon emissions and ambition of carbon neutrality, renewable fuels synthesized from biomass have great application prospects. Herein we adopted hydrogenation and cyclopropanation to synthesize four biofuels using α-cedrene and longifolene as feedstocks. Specifically, the modified Simmons-Smith method was used to synthesize cyclopropanated biofuels with a yield greater than 80% under the optimized conditions. The as-prepared biofuels possess the density of 0.925–0.965 g/mL, and the volumetric energy of 39.45–41.51 MJ/L. Additionally, the minimum ignition temperature and ignition delay time of the synthesized biofuels are shortened by 46–108 °C and 27.0–71.4%, respectively, compared with the widely used JP-10 fuel. The synthesized sesquiterpene-based biofuels have good potential to as alternative of high energy density fossil fuels like JP-10.

A Secured Zobrist Hash Symmetric Sentinel List Based Malicious Attack Detection in Vanet

VANET enables communication between the vehicles and Road Side units (RSUs). With the ever fast growth in industry and research necessitates the design of smart transportation system. Moreover, VANET success lies in the security features provided and it cannot be achieved precisely due to all type of security attacks. To secure the VANET against these types of security attacks, most of the research persons have proposed different security mechanisms based on lightweight and one way hash function. While both lightweight and one way hash function are efficient to certain degree, each method has some weakness to entirely secure the network. In this paper, we propose a list-based malicious attack detection scheme based on Zobrist Hash, called, Secured Zobrist Hash Symmetric Attack Detection (SZ-HSAD) to secure VANET to a larger extent. A system initialization is an essential part of trust establishment and secure communications between vehicles, the proposed SZ-HSAD integrates symmetric cryptography based initialization for efficient and robust trust management scheme. The system initialization includes Zobrist Hash Optimal Distance Registration. The trusted authority (TA) evaluates key for both the Road Side Unit (RSU) and vehicles based on the identity. Next, a list-based malicious attack detection using symmetric and sentinel node is designed for timely and early attack detection in VANET. The results are acquired with immense simulations to validate the proposed scheme. The results show that the proposed scheme converge security prerequisites, therefore reducing the average traffic overhead with minimum execution time and verification delay.

Simultaneous Constraints on the Star Formation History and Nucleosynthesis of Sculptor dSph

Abstract We demonstrate that using up to seven stellar abundance ratios can place observational constraints on the star formation histories (SFHs) of Local Group dSphs, using Sculptor dSph as a test case. We use a one-zone chemical evolution model to fit the overall abundance patterns of α elements (which probe the core-collapse supernovae that occur shortly after star formation), s-process elements (which probe AGB nucleosynthesis at intermediate delay times), and iron-peak elements (which probe delayed Type Ia supernovae). Our best-fit model indicates that Sculptor dSph has an ancient SFH, consistent with previous estimates from deep photometry. However, we derive a total star formation duration of ∼0.9 Gyr, which is shorter than photometrically derived SFHs. We explore the effect of various model assumptions on our measurement and find that modifications to these assumptions still produce relatively short SFHs of duration ≲1.4 Gyr. Our model is also able to compare sets of predicted nucleosynthetic yields for supernovae and AGB stars, and can provide insight into the nucleosynthesis of individual elements in Sculptor dSph. We find that observed [Mn/Fe] and [Ni/Fe] trends are most consistent with sub-M Ch Type Ia supernova models, and that a combination of “prompt” (delay times similar to core-collapse supernovae) and “delayed” (minimum delay times ≳50 Myr) r-process events may be required to reproduce observed [Ba/Mg] and [Eu/Mg] trends.

ЗАСТОСУВАННЯ ГЕОІНФОРМАЦІЙНИХ СИСТЕМ ДЛЯ ВИРІШЕННЯ ЗАВДАНЬ НАВІГАЦІЙНОГО ЗАБЕЗПЕЧЕННЯ ВІЙСЬК

Rapid implementation of computer and information technologies in the activities of the troops (forces) is currently taking place, namely, significant successes in the use of geographic information systems (GIS) are noted. Modern GIS in the armed forces of other countries has also found wide application in the operational training of military C2 bodies, information support of combat actions, updating topographic maps, determining the location of the position of troops and individual servicemen, as well as in other areas of military activity. Therefore, it is necessary to analyze the most successful technologies and move towards their implementation. Currently, a large part of geographic information changes rapidly with time, which makes the use of traditional maps irrelevant. GIS is a software and technical complex that allows you to combine a model image of the territory with tabular information. The software and technical complex provides automated collection, processing, analysis, storage, display and distribution of spatially coordinated information. A computer system that makes it possible to edit, use, store, analyze and display graphic data in a cartographic form. GIS provide the most complete creation and timely restoration of the cartographic base. First of all, it concerns different types of cards. In addition, it is now possible to receive aerial, photographic and space images of local objects with minimal time delay, with the possibility of obtaining their specific characteristics. The speed of receiving information can only be guaranteed by a modern automated system with the possibility of documenting the provided information. The system allows you to create vector, raster and matrix maps, as well as quickly update various information about the area.

Novel design of PID controllers for minimum and non-minimum phase time delay processes for enhanced performance

A new technique is proposed for the design of PID controllers for minimum and non-minimum phase (NMP) stable first-order and second-order processes. The idea is to make the open-loop transfer function model equal to an integrating model with which the closed loop consists of first order dynamics. The resulting controller settings are functions of the tuning factor δ and process model parameters. The tuning parameter is selected based on the stability and robustness margins. Different case studies for simulation and experimental implementation are considered and the closed loop responses are examined. The proposed technique gives enhanced closed-loop performance for both set point and regulatory problems compared to the current techniques in both perfect and perturbed model conditions. Performance metrics such as integral error, control variation, stability margins, and sensitivity peak are compared and it is noted that the enhanced responses are achieved with the proposed simple method, which has straightforward simple analytical relations for design of the controller.

Novel design of PID controllers for minimum and non-minimum phase time delay processes for enhanced performance

Novel design of PID controllers for minimum and non-minimum phase time delay processes for enhanced performance

Two novel heterobimetallic metal-organic frameworks for the enhanced catalytic thermolysis and laser ignition of CL-20

The study of multiple complex catalytic mechanisms is currently one of the great scientific issues for the application of high-energy solid propellants. Two novel heterobimetallic metal-organic frameworks (MOFs), Ba4Pb4(CH3CO2)8 [(CH6CO2)4Pb](CH3CO2)4 (PbBa-MOF) and Ba2Ni(CO2H)6(OH2)4 (NiBa-MOF), were prepared via the solvothermal method, and their structures and composition were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FTIR) techniques and N2 adsorption/desorption experiment. The thermal decomposition characteristics of the two MOFs and their catalytic performances on the hexanitro hexaazaisowurtzitane (CL-20) thermolysis were also studied by differential scanning calorimetr (DSC) and thermogravimetric-fourier transform infrared spectroscopy-mass spectrum (TG-FTIR-MS) methods. The results showed that the NiBa-MOF presented a lower initial decomposition temperature than the PbBa-MOF, and the difference of the MOFs structures affected the starting point of thermal decomposition. Compared with the pure CL-20, the thermolysis peak temperature and apparent activation energy (Ea) of the CL-20/PbBa-MOF mixture were decreased by 2.2 °C and 23.76 kJ‧mol−1, respectively. The Ea of CL-20/NiBa-MOF mixture was lower and 42.01 kJ‧mol−1, indicating the better catalytic activity of NiBa-MOF. The thermolysis catalytic mechanisms were studied by analyzing the transformation of gas products during the pyrolysis of mixtures. The effect of these two MOFs on the CL-20 thermolysis is primarily owing to the strong attraction of metal cations to electronics, bimetallic synergistic catalysis, and the release of active free radicals. Furthermore, the laser ignition and flame propagation features showed that these two MOFs reduced the minimum ignition power density and ignition delay time of the CL-20, and the flame becomes brighter and more luminous. The influence of the two MOFs on the flame bright spot of CL-20 based mixtures was described.

Real-Time Gait Event Detection for a Lower Extremity Exoskeleton Robot by Infrared Distance Sensors

Gait event detection is a crucial part in the motion control and performance evaluation of exoskeleton robots. To detect the whole gait events conveniently and effectively, a wearable system based on infrared distance sensors is proposed. The heel and toe clearances were used for the first time for the online detection of all six gait events in one gait cycle. Smart shoes integrated with three infrared distance sensors were designed to obtain stable distance signals, which were then converted into effective foot posture information. Moreover, an online detection algorithm was proposed using local search windows and fixed thresholds, resulting in a minimal time delay and a small computational burden. By comparing the system with the motion capture system at different walking speeds, the average detection error of gait events is within 34ms, and the average detection rate of the system is 99.62%. When applied to a lower extremity exoskeleton robot, the system successfully detects all gait events of the human-robot synchronous walk. The results show that the system has good real-time performance and high detection rate. This study provides a convenient and reliable detection method for gait research of human body and exoskeleton robots.

Dual-wavelength flash Raman mapping method for measuring the thermal diffusivity of a single supported nanowire

The heat dissipation of electronic devices has become an enormous challenge with the dramatic increasing of integrated transistors on a chip. Nanowires are viewed as promising materials for solving this problem. The accurate measurement of thermal diffusivity is a precondition for further applications. This paper presents a non-destructive method to measure the thermal diffusivity of a single supported nanowire, which is called dual-wavelength flash Raman (DFR) mapping method. This method has a 100 ps temporal resolution based on the minimum time delay between the heating and probing laser pulses and 50 nm spatial resolution based on the minimum step of the probing pulse. Compared with previously proposed concentric DFR method, the probing pulse can move along the nanwire length and the movable probing laser beam allowed temperature measurements at the most sensitive position,which improves the measurement accuracy by 50%. Moreover, instead of the normalizaiton temperature method in concentric DFR method, a temperature phase method was proposed for analyzing the temperature variation curves. The measurements on a single supported silicon nanowire verified the reliability of the DFR mapping method. One thousand virtual experiments showed that the uncertainty of this method can achieve ±5%.

Intelligent Transport System Using Time Delay-Based Multipath Routing Protocol for Vehicular Ad Hoc Networks.

During the last decade, the research on Intelligent Transportation System (ITS) has improved exponentially in real-life scenarios to provide optimized transport network performance. It is a matter of importance that alert messages are delivered promptly to prevent vehicular traffic problems. The fact is an ITS system per se could be a part of a vehicular ad hoc network (VANET) which is an extension of a wireless network. In all sorts of wireless ad hoc networks, the network topology is subjected to change due to the mobility of network nodes; therefore, an existing explored route between two nodes could be demolished in a minor fraction of time. When it comes to the VANETs, the topology likely changes due to the high velocity of nodes. On the other hand, time is a crucial factor playing an important role in message handling between the network’s nodes. In this paper, we propose Time delay-based Multipath Routing (TMR) protocol that effectively identifies an optimized path for packet delivery to the destination vehicle with a minimal time delay. Our algorithm gives a higher priority to alert messages compared to normal messages. It also selects the routes with the short round-trip time (RTT) within the RTT threshold. As a result, our algorithm would realize two goals. Firstly, it would speed up the data transmission rate and deliver data packets, particularly warning messages, to the destination vehicle promptly and therefore avoid vehicular problems such as car accidents. Secondly, the TMR algorithm reduces the data traffic load, particularly of the normal messages, to alleviate the pressure on the network and therefore avoids network congestion and data collisions. This, in turn, lessens the packets’ retransmissions. To demonstrate the effectiveness of the proposed protocol, the TMR has been compared with the other protocols such as AOMDV, FF-AOMDV, EGSR, QMR, and ISR. Simulation results demonstrate that our proposed protocol proves its excellent performance compared to other protocols.

The intra-day optical monitoring of BL Lacerate object 1ES 1218+304 at its highest X-ray flux level

We here report a monitor of the BL Lac object 1ES 1218+304 in both B- and R-bands by the GWAC-F60A telescope in eight nights, when it was triggered to be at its highest X-ray flux in history by the VERITAS Observatory and Swift follow-ups. Both ANOVA and χ 2-test enable us to clearly reveal an intra-day variability in optical wavelengths in seven out of the eight nights. A bluer-when-brighter chromatic relationship has been clearly identified in five out of the eight nights, which can be well explained by the shock-in-jet model. In addition, a quasi-periodic oscillation phenomenon in both bands could be tentatively identified in the first night. A positive delay between the two bands has been revealed in three out of the eight nights, and a negative one in the other nights. The identified minimum time delay enables us to estimate the M BH = 2.8 × 107 M ⊙that is invalid.

The surface activation of boron to improve ignition and combustion characteristic

Boron is a very promising and highly attractive fuel because of high calorific value. However, the practical applications in explosives and propellants of boron have been limited by long ignition delay time and low combustion efficiency. Herein, nano-Al and graphene fluoride (GF) as surface activated materials are employed to coat boron (B) particles to improve ignition and combustion performance. The reaction heat of nano-Al coated B/KNO3 and GF coated B/KNO3 are 1116.83 J/g and 862.69 J/g, respectively, which are higher than that of pure B/KNO3 (823.39 J/g). The ignition delay time of B/KNO3 could be reduced through nano-Al coating. The shortest ignition delay time is only 75 ms for B coated with nano-Al of 8 wt%, which is much shorter than that of pure B/KNO3 (109 ms). However, the ignition delay time of B/KNO3 coated with GF has been increased from 109 to 187 ms. B coated with GF and nano-Al shown significantly influence on the pressure output and flame structure of B/KNO3. Furthermore, the effects of B/O ratios on the pressure output and ignition delay time have been further fully studied. For B/KNO3 coated with nano-Al and GF, the highest pressures are 88 KPa and 59 KPa for B/O ratio of 4:6, and the minimum ignition delay time are 94 ms and 148 ms for B/O ratio of 7:3. Based on the above results, the reaction process of boron coated with GF and nano-Al has been proposed to understand combustion mechanism.

Determination method of tunnel blasting parameters using electronic detonator under changing condition of free surface

The technical potential of electronic detonator has not yet been fully utilized in tunnel engineering. An important reason is that there is no calculation method of blasting parameters supported by rigorous theory. The pivotal blasting parameters such as charge and delay time, etc. are mostly designed following ordinary mining method. And it can not solve the problem of calculation accuracy of blasting parameters after the formation of the second free surface. Taking Guanyinqiao Tunnel in Chongqing as the research background, based on the Anderson principle and the delay characteristics of the electronic detonator, a new method for designing the blasting parameters of electronic detonator is proposed under the different free surface conditions changing in the process of tunnel blasting, from single free surface to dual free surface. Firstly, based on the single-hole and single free surface blasting vibration curves of different charges acquired on site, the superimposed vibration of multiple blast-holes under each delay time was calculated one by one. After comparing the superimposed vibration curves of different charges and delays, it was determined the blasting parameters of single free surface, including the maximum single-hole charge and the optimal inter-hole delay. Secondly, according to the characteristics of the electronic detonator, the short-delay cut blasting field test was designed. By comparing the calculated waveform without considering the influence of the second free surface with the measured waveform affected by the vibration reduction effect of the second free surface, it was found that the second free surface had formed at 48 ms after initiation. Based on this, a single-hole blasting test was designed after the formation of the second free surface. By calculating the superimposed vibration velocity based on the single-hole waveforms before and after the formation of the second free surface, it was determined the blasting parameters under the dual free surfaces condition, including single-hole charge, inter-hole delay time, and delay between different types of holes. Finally, the calculation method of blasting parameters in the whole blasting process was formed. After the comprehensive analysis of the calculated results, the single-hole charge of the main cutting holes is 1.2 kg, and it is 1.4 kg of the auxiliary cutting holes, then the delay time between holes is 5 ms on site; the minimum delay time between the main cut holes and the auxiliary cut holes is 35 ms. The field test was carried out with the optimized parameters mentioned above, and it got high-efficiency footage as well as a low vibration velocity.

A Sealed-Off Pseudospark Switch With Nanosecond Stability of Triggering

This article describes the modified version of the commercially produced pseudospark switch TPI1-10k/50 (pulsed current-10 kA and anode voltage-up to 50 kV) and the results of testing. The main idea of the modification was to use the high-voltage electrode system of this switch but to incorporate the novel trigger unit in the main cathode cavity. This unit uses the auxiliary glow discharge with hollow cathode and hollow anode. The modified switch is intentionally developed for parallel operation of a large number of the switches to a common load. In such conditions, the nanosecond triggering stability of the switches is required. The results of tests demonstrate that the minimum delay time of triggering (the time interval between the instant of arrival of the trigger pulse and the instant of starting the main discharge current) amounts to 80 ns with a jitter of 3 ns. At a decreased hydrogen pressure, the delay time is not increased essentially and amounts to 105 ns with a jitter of 6 ns.

Research on multi-objective optimal scheduling considering the balance of labor workload distribution.

In order to solve the problem of unbalanced workload of employees in parallel flow shop scheduling, a method of job standard balance is proposed to describe the work balance of employees. The minimum delay time of completion and the imbalance of employee work are taken as the two goals of the model. A bi-objective nonlinear integer programming model is proposed. NSGA-II-EDSP, NSGA-II-KES, and NSGA-II-QKES heuristic rule algorithms are designed to solve the problem. A number of computational experiments of different sizes are conducted, and compared with solutions generated by NSGA-II. The experimental results show the advantages of the proposed model and method, which error is reduced 14.56%, 15.16% and 15.67%.