Behavioral Simulation Research Articles

FPGA Implementation of High Speed Digital Pulse Width Modulator (DPWM) Technique for DC-DC Converter

Objectives: Digital Pulse Width Modulator (DPWM) remains essential element in power controlling devices that command power switch of power converters. The focus of this study is to structure DPWM of FPGA base for DC chopper. Methods: Buck, Boost, Buck and Boost convertor versions are developed in MATLAB-SIMULINK. Verilog coding is performed for Digital Controller to operate for greater rates, which may be incorporated in high speed surroundings; synthesis is completed utilizing Xilinx ISE, along with Behavioral and Period simulation performed with Xilinx Simulator. After affirmation of code it is downloaded on FPGA Spartan 3AN board. The output is confirmed by means of Oscilloscope. Findings/Application: The resulting DPWM is a high speed and less power consuming architecture for Buck, Boost, Buck and Boost DC-DC converter. The utilization of Gray counter and One-hot encoder in DPWM has helped in speed improvement and reduced power consumption. The grey encoding method has fewer states in comparison with the sequential encoding method, which makes them quicker. The output is a Pulse-Width Modulation (PWM) signal, for varying clock frequency and duty cycle. The power consumed by DPWM for various frequencies was verified in comparison with the high frequency DPWM. For 6 MHz frequency, the power consumed by DPWM is 0.01486 w and that by a high frequency DPWM is 0.01486 w. The proposed DPWM can operate at a maximum frequency of 140.298 MHz. This DPWM is best suited for Buck, Boost, and Buck and Boost DC-DC converters. Keywords: DC–DC Converter, Field Programmable Gate Arrays (FPGA), Pulse-Width Modulation (PWM), Spartan, MATLAB, SIMULINK

An investigation into serotonergic and environmental interventions against depression in a simulated delayed reward paradigm

The disruption of the serotonergic (5HT) system has been implicated in causing major depression and the standard view is that a lack of serotonin is to blame for the resulting symptoms. Consequently, pharmacological interventions aim to increase serotonin concentration in its target areas or stimulating excitatory 5HT receptors. A standard approach is to use serotonin reuptake inhibitors (SSRIs) which cause a higher accumulation of serotonin. Another approach is to stimulate excitatory serotonin receptors with psychedelic drugs. This article compares these two approaches by first setting up a system-level limbic system model of the relevant brain areas and then modelling a delayed reward paradigm which is known to be disrupted by a lack of 5HT. Central to our model is how serotonin changes the response characteristics of decision-making neurons where low levels of 5HT allow small signals to pass through, whereas high levels of 5HT create a barrier for smaller signals but amplifying the larger ones. We show with both standard behavioural simulations and model checking that SSRIs perform significantly better against interventions with psychedelics. However, psychedelics might work better in other paradigms where a high level of exploration is beneficial to obtain rewards.

The Crucible simulation: Behavioral simulation improves clinical leadership skills and understanding of complex health policy change.

The Health and Social Care Act 2012 represents the most complex National Health Service reforms in history. High-quality clinical leadership is important for successful implementation of health service reform. However, little is known about the effectiveness of current leadership training. This study describes the use of a behavioral simulation to improve the knowledge and leadership of a cohort of medical doctors expected to take leadership roles in the National Health Service. A day-long behavioral simulation (The Crucible) was developed and run based on a fictitious but realistic health economy. Participants completed pre- and postsimulation questionnaires generating qualitative and quantitative data. Leadership skills, knowledge, and behavior change processes described by the "theory of planned behavior" were self-assessed pre- and postsimulation. Sixty-nine medical doctors attended. Participants deemed the simulation immersive and relevant. Significant improvements were shown in perceived knowledge, capability, attitudes, subjective norms, intentions, and leadership competency following the program. Nearly one third of participants reported that they had implemented knowledge and skills from the simulation into practice within 4 weeks. This study systematically demonstrates the effectiveness of behavioral simulation for clinical management training and understanding of health policy reform. Potential future uses and strategies for analysis are discussed. High-quality care requires understanding of health systems and strong leadership. Policymakers should consider the use of behavioral simulation to improve understanding of health service reform and development of leadership skills in clinicians, who readily adopt skills from simulation into everyday practice.

VCO-Based ADC With Built-In Supply Noise Immunity Using Injection-Locked Ring Oscillators

Analog-to-digital converters (ADCs) based on voltage-controlled oscillators (VCOs) demonstrate superior hardware efficiency. They benefit from the technology scaling; however, they exhibit inferior performance against supply noise. The objective of this brief is, therefore, to present a VCO-based ADC architecture with built-in immunity against supply noise. The proposed technique exploits the dynamics of injection locking oscillation in multiphase ring topology. It provides a system-level cancelling of power supply noise, independent of the VCO architecture used in the time-mode ADC. The design functionality has been demonstrated using behavioral and transistor-level simulations using 65 nm technology. Under a 10% mismatch of VCO gain and a 128 MS/s data rate, the reported power supply noise rejection improvement is 25 dB, as compared with a typical VCO-based ADC.

Calibrating Amplifiers Nonlinearity Using Comparator-Based ADCs

Amplifiers are widely used within analog-to-digital converters (ADCs) to buffer and increase signal amplitude, alleviating the accuracy, noise, and power constraints of the ADCs. However, any nonlinearity caused by front-end amplifiers is fully or partially inherited by the ADC, compromising its overall linearity. Additionally, as CMOS processes scale, amplifiers become increasingly difficult to design due to reduced intrinsic gain and voltage headroom. Many applications rely on digital calibration to alleviate the amplifier specifications, which may use polynomial fitting or another sort of digital processing. Despite reducing the analog power, these solutions render high complexity and power consumption on the digital part. In this brief, we describe how comparator-based ADCs, such as a flash ADC or a comparator-based asynchronous binary search (CABS) ADC, inherently provide sufficient degrees of freedom to calibrate any monotonic nonlinearity. Then, we exploit this property to propose a low-complexity, low-power, and low-overhead calibration scheme, where we embed the inverse transfer function of the nonlinear amplifier into the decision thresholds of the following ADC. We also propose a statistical-driven algorithm that is used to guide the thresholds adjustment in the background. Finally, we extensively validate the proposed approach through behavioral simulations.

Digital-to-Frequency Converters With a DTC: Theoretical Analysis of the Output SFDR

In this paper, we propose and analyze a pulse-output digital-to-frequency converter (DFC) generating square waves, which uses a digital-to-time converter (DTC) to correct the spurious tones (spurs) in the output spectrum. We focus on high-level architectural potential, discuss the design features of a DTC suitable for the proposed system, and explore possibilities and limits of this approach in terms of cleanness of the output spectrum. The behavioral model simulations confirm the theoretical analysis presented. Besides an analytical description of the output spurs, we derive a closed-form estimate of the worst-case spur, which leads to a simple design equation. This is useful to determine the DTC requirements [number of bits and integral non-linearity (INL)], given a certain spurious-free dynamic range (SFDR) target. We show that the maximum spur strength (in dBc) depends exclusively on the ratio between the output frequency and the clock frequency and the DTC features (number of bits, INL, and other impairments) and increases with the ratio by 6 dB/octave.

Cross-Layer Behavioral Modeling and Simulation of E/E-Architectures using PREEvision and Ptolemy II

In this paper, an approach for integrated behavior modeling and simulation within model-based electric/electronic-architecture (EEA) descriptions is presented. It leverages actor-oriented and UML state chart behavior modeling to address complex reactive systems. A key contribution is the aggregation of cross-layer behavior specified at the logical function architecture layer and at the hardware layer together with further properties of the EEA, such as the current consumption of electronic control units (ECUs), the underlying network topology and execution aspects of functions. The EEA and behavior modeling is done in the common industry tool PREEvision. Using these static descriptions, a unified simulation model is synthesized and executed using Ptolemy II, which extends a previously developed approach. In addition, a general concept to feed back the simulation data into PREEvision is briefly described e.g., to further evaluate the gained results. Finally, a proof-of-concept is presented using an Adaptive Cruise Control application.

A Safety Evaluation of the Impact of Maternity-Orientated Human Factors Training on Safety Culture in a Tertiary Maternity Unit.

Human factors have risen to attention in maternity as key contributors to patient harm. Despite national recommendation for multidisciplinary human factors training, there is a lack of guidance and healthcare-orientated training. The aim of the study was to evaluate the impact of maternity-orientated human factors training program on safety culture in a tertiary maternity unit. This prospective observational cohort study was conducted for 6 months in a tertiary maternity unit. Participants involved in high-risk intrapartum care completed the Hospital Survey of Patient Safety Culture before and after intervention. Statistical analysis was performed using the χ test with statistical significance at 5% (P = 0.05). The human factors curriculum included situational awareness, communication, decision-making, conflict resolution, teamwork, and leadership. A train-the-trainer approach generated a faculty to disseminate multidisciplinary training. Traditional classroom teaching, social media content, and cognitive activities provided theoretical foundations. Forum theater and behavioral simulation taught complex communication issues. Regular labor ward simulations helped embed training into clinical practice. The results demonstrated statistically significant improvement in safety culture domains of communication openness, handover, nonpunitive response to error, and overall safety perception. Participants felt more able to challenge decisions or actions of those in authority, 33% responded "most of the time or always" in August increasing to 42% in January with a reduction of 50% in those responding "never" (P = 0.02). No change was found relating to team working, staffing or manager expectations promoting patient safety. This study is proof-of-concept that maternity-orientated human factors training can improve safety culture.

Implementation proposal for an ancillary service for Island Operation Capability in Colombia: A system dynamics approach

The Island Operation Capability service allows operators to split the system (in case of an accident, for instance) and operate as an integral isolated subsystem. This, in turn, increases reliability, resilience, efficiency, and reduces restoration times after a blackout in the islands power systems. The provision of this kind of service from distributed energy resources has recently been introduced in different power systems. This paper outlines a proposal for the implementation of Island Operation Capability in the Colombian electricity market. The proposal considers technical variables, namely, energy not supplied, generation not delivered, and electrical losses. We developed a behavioral simulation model to test the impact of the implementation and an upgrade of the grid. Simulation results show technical benefits for the distribution system operator and economic benefits for investors and project promoters of distributed energy resources. Finally, the simulation’s results show that modernizing the distribution grid is important in order to increase Island Operation Capability and the security of the electrical system.

Two novel architectures for 4-channel mixing/filtering/processing digitizers

Two architectures of 4-channel mixing-filtering-processing (MFP) digitizers are presented and compared. Both architectures use four analogue-to-digital converters (ADCs), but differ in terms of layout, and are named parallel and hierarchical, respectively. The hierarchical architecture is entirely novel, while the parallel one is at present only envisaged in patent documents. For both architectures, a suitable analytical model, used to determine the effects of several error sources, is provided. Also, digital signal processing techniques, which combine the digitized streams produced by the four ADCs to compensate the errors, are illustrated for both architectures. The computational cost of these techniques, implemented by means of poly-phase filters, is discussed, and their capability of attaining real time performance highlighted. The results of behavioral simulations carried out to assess the performance of the two 4-channel MFP architectures are finally shown.

Analysis and performance of coded symbol recovery loop using oversampling

In this work, we propose a closed-loop analog system to detect the source information of a binary data stream coded by a flexible finite automaton. We initially consider the dual sideband suppressed-carrier modulation of a base band binary amplitude waveform. The automaton introduces a symbol redundancy as phase contribution of the modulated signal by a simple mapping scheme. The proposed recovery system performs a coherent demodulation, presenting the base-band binary wave to a maximum likelihood hard detector, a simple analog trigger that estimates the source data within the symbol period. This wave is over-sampled, and the final decision comes by counting the positive samples and a majority vote. We prove our approach is valid answering the most important concerns: the stability of the closed loop, a first analytical expression of the error rate when a Markov birth process models the counting phase, and finally the role of this last loop to lower the bit error rate compared to a simple Costas loop. The analysis continues by solving the problem of carrier and symbol rate recovery and the impact of non-linearity and noise in the basic analog blocks. Behavioral simulations describe a competitive scenario in terms of error rate, comparing the proposed approach to the Costas Loop and the basic convolutional decoding strategies based on Viterbi algorithm both in the hard (Hamming metrics) and soft (Euclidean metrics) versions.

Behavioral game and simulation analysis of extended producer responsibility system's implementation under environmental regulations.

The implementation of the extended producer responsibility (EPR) for e-waste is an important measure to develop an ecological civilization. In order to advance manufacturing enterprises to effectively implement resource and environmental responsibility, this study investigates the main causes of environmental regulation failure from the perspective of government and enterprises. The game theory was used to establish an evolutionary game model between government regulatory departments and electronic and electrical products' manufacturing enterprises. A system dynamic model was utilized to construct the stock-flow graph of the game between government and enterprises, and to carry out simulation analysis under different strategies. The results found that the probability of an enterprise undertaking extended responsibility gradually increased and stabilized with the increase of government supervision and punishment intensity; the government's regulatory probability and punishment are important factors affecting the enterprises' compliance with regulations and responsibilities. The study suggests that government should focus on strengthening environmental regulations from the aspects of improving laws and regulations, establishing a regular monitoring system and innovating incentive and constraint mechanism.

A Split-Based Digital Background Calibration of Pipelined Analog-to-Digital Converters by Cubic Spline Interpolation Filtering

In this paper, a digital background calibration technique for pipelined analog-to-digital converter (ADC) based on the concept of split architecture is proposed to address finite dc gain and nonlinearity of the residue amplifier. In the proposed method, the pipelined ADC divided into two channels where each channel included the first stage followed by an ideal backend ADC. A 1.5 bit per stage is chosen for the first stage of each channel where a pseudorandom sequence is injected before one of the channels. The difference between the digital outputs of two channels is used to drive an interpolation filter to correct the mentioned errors. Since splines modeled high nonlinearity with weakly nonlinear functions, it selected for interpolation filtering which results in low computational overhead and fast convergence time. Behavioral simulations of a 12-bit 100 MS/s pipelined ADC show that the convergence time of the algorithm is approximately 4 × 104 clock cycles and the signal-to-noise and distortion ratio and the spurious free dynamic range improved from 32 dB/35 dB to 70 dB/75 dB.

Reduced-Code Static Linearity Test of Split-Capacitor SAR ADCs Using an Embedded Incremental <inline-formula> <tex-math notation="LaTeX">$\Sigma\Delta$ </tex-math> </inline-formula> Converter

Reduced-code techniques for an analog-to-digital converter (ADC) static linearity test have the potential to drastically reduce the number of necessary measurements for a complete static linearity characterization. These techniques take advantage of the repetitive operation of certain families of converters such as pipelines, successive-approximation registers (SARs), cyclic, etc. In this paper, we present a novel reduced-code technique for the static linearity test of split-capacitor SAR ADCs based on the on-chip generation and measurement of the major carrier transitions of the input digital-to-analog converter of the converter. The proposed test method does not require a test stimulus, and we show that the necessary measurements can be easily extracted by reconfiguring portions of the SAR into a low-resolution incremental ${\Sigma \Delta }$ converter. The proposed technique is validated with both behavioral and electrical simulations of a 10-bit SAR ADC in a 65-nm CMOS technology.

An Accurate and Noise-Resilient Spread-Spectrum Clock Tracking Aid for Digitally-Controlled Clock and Data Recovery Loops

This paper presents a novel spread-spectrum clock (SSC) tracking aid for digitally-controlled clock and data recovery (CDR) loops. The proposed tracking aid accurately recovers the time instants when the slope of the incoming data frequency ramp changes its polarity, so that the CDR can pre-emptively compensate the timing errors that can otherwise be incurred when relying on feedback controls only. Compared with the existing SSC tracking aids, the proposed tracking aid’s integration-based mean-tracking loop, comprising an integrator and subsequent negative feedback loop, achieves the superior noise resilience and SSC timing accuracy. The analysis shows that the error in recovering the SSC deflection timing can be as low as 0.01% of the SSC modulation period in case of tracking a triangular SSC profile and the error does not exceed 1.5% even when the SSC profile noise is increased to the signal-to-noise-plus-distortion ratio of 20 dB. The behavioral simulation of a digitally-controlled phase-locked loop (PLL)-based CDR employing the proposed SSC tracking aid demonstrates a 0.711-UI timing margin with a BER of 10−12, which is a $1.57\times $ improvement in comparison with a PLL-based second-order CDR, when tracking a 6-Gb/s data stream modulated with a 30-kHz, 50000-ppm extended triangular-shaped SSC profile.

Design challenges for a new mostly digital VCO‐based delta‐sigma modulator

This study presents an architecture and study of closed-loop continuous time delta-sigma modulation utilising only voltage-controlled oscillators (VCOs) and digital elements. It incorporates a VCO-based integrator in which the offset due to the carrier frequency ( f c ) is digitally subtracted. Unlike some prior structures, an extra VCO for reference signal generation is not necessary which can lead to a reduction in power consumption, area and noise. In addition, in comparison to a recently reported structure, the VCO is placed inside the feedback loop, so the input signal swing of the VCO is decreased and the linearity is improved. However, the proposed structure suffers from two noise folding effects at low frequencies which degrade the dynamic range of the modulator. These two noise folding effects will be analysed and it will be shown that these problems can be tackled by the right choice of f c and appropriate design. Behavioural simulations are done for the proposed structure to confirm the structure's performance.

Joint background calibration of gain and timing mismatch errors with low hardware cost for time‐interleaved ADCs

A joint background calibration scheme is proposed for the gain and timing mismatch errors in time-interleaved analogue-to-digital converts (TI ADCs). Mixed-signal calibration is adopted for timing mismatch without using correlators or multi-tap digital filters, while the gain mismatch is estimated and calibrated all digitally based on the moving average of the derivative for each channel's output. Therefore, the influence of offset mismatch on the estimation accuracy of the gain error can be eliminated completely. To reduce hardware cost as much as possible, most of the arithmetic blocks are reused for gain and timing mismatch estimation. Behavioural simulation with a 12 bit, 2 GSPS two-channel TI ADC and measurement results from a commercial 12 bit 3.6 GSPS two-channel TI ADC show that the proposed joint calibration scheme can effectively correct the gain and timing mismatch errors.

Study of collective nutrition education sessions for diabetic type II patients

As with many chronic diseases, most French diabetes services for patients with type II diabetes now have a structured reception approach including collective educational sessions in the form of targeted workshops, thematic days, or even programs with several sessions. The aim of our study is to understand the interlocutory dynamics favorable to the adoption of new cognitions and attitudes during these sessions. We studied the verbal exchanges of nine collective nutrition education sessions (five focusing on knowledge input, and four implementing behavioral simulation). A total of 76 patients with type II diabetes (per group of six to 13 participants) and 12 group leaders (nurses, dieticians or nutritionists) contributed to this study, based on audio recording, and analysis of these sessions lasting two hours on average (with between 4345 and 8592 words per session). The nine corpora were the subject of two types of content analysis: lexical and dialogic, with the N'vivo 8 software. The results of this study suggest very precisely several ways to improve the content of the informational contributions of these educational sessions. The study of their process also makes it possible to distinguish between self-disclosure and social support in communication between participants. Finally, this study checks the effectiveness of the different types of framing of health messages in the discourse of the group leaders to facilitate the adhesion of the participants. In conclusion, it appears that the reaction spontaneously verbalized by the participants during the course of the educational situation, in these sessions, can be considered as an interesting indicator of their impact. The results may have implications for the development of nutritional education programs and group leader training.

Examining interrelationships between the Cigarette Purchase Task and delay discounting among pregnant women.

Two common behavioral economic simulation tasks used to study cigarette smoking are the Cigarette Purchase Task, a measure of cigarette demand, and delay discounting, a measure of the subjective value of rewards as a function of delays to delivery. Few studies have evaluated whether combining these tasks enhances understanding of smoking beyond either alone. The current study represents an initial evaluation of the intersection between cigarette demand indices and delay discounting among pregnant smokers by examining associations between these measures and whether a woman makes antepartum quit attempts before entering prenatal care (a reliable predictor of eventual quitting). Participants were 159 pregnant women enrolled in a smoking-cessation trial. Low O max and shallow discounting were each associated with antepartum quit attempts. Participants were next categorized into four subgroups (low O max , shallow discounting; low O max , steep discounting; high O max , shallow discounting; high O max , steep discounting) using median splits. Those with shallow discounting and low O max were more likely to have made quit attempts than each of the other three subgroups. That is, steep discounting appears to undermine the association of low O max and efforts to quit smoking during pregnancy while high O max overshadows any protective influence associated with shallow discounting.

SIMULATION TECHNOLOGIES IN THE MODELLING USERS’ BEHAVIORS IN THE PHARMACEUTICAL MARKET

The creation of a new branch of economics – behavioural economics studying the features of decision-making, resulted in changes of a number of fundamental ideas. The modern view of the economy, as a complex adaptive system, makes it necessary to use new methodologies for modeling dynamic processes, events arising over time, reproduce and transform.The apparatus of simulation modeling based on three main paradigms - Discrete Event, System Dynamics, and Agent Based - and their combinations meets these requirements Modeling the ‘arising’ behaviour of economic agents and developing forecasting models of commodity markets became possible with the advent of behavioural economics and simulation technologies. The domestic pharmaceutical market is one of the most dynamic, flexible and highly competitive, and the pharmaceutical industry is one of the active and gradually growing sectors of the Ukrainian economy. The need for taking into consideration its relationship to healthcare (with a significant range of specific agents), the active implementation of information and communication technologies, the emergence of a new type of users with complicated behaviour and a dynamic change in the preferences determines the relevance of conducting a special research of the pharmaceutical market. At the same time, application of such flexible tools as simulation technologies is gaining particular importance. The objective of this article is the reveal the possibilities of using simulation technologies in modeling the user’s behaviour in the pharmaceutical market. The article presents the results of the experiments conducted on the simulation models of consumer behavior of original and generic medicines in terms of working out their sales promotion strategies. The models are developed using the multi-level simulation paradigm (a combination of Agent-Based and System Dynamics approaches) on the platform of the AnyLogic system. In the experiments, materials from leading pharmaceutical companies of Ukraine were used. The experiments have proved the possibility to reproduce the consumers’ behaviour in dynamics, taking into account the influence of numerous stochastic factors in the market environment. Models are offered for use in the process of making managerial decisions on the production and sales of products by pharmaceutical enterprises. Models can be tailored to the specifics of a particular enterprise.