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1.
Analog integrated circuit design has as integral parts both analytical reasoning and numerical validation in the process from topology construction to sizing. Given a circuit topology, different circuit sizing results can be obtained from different processes of sizing inference. Sizing methods by simulation-based numerical searching have been a continuously studied subject. However, almost all approaches in this category require an overwhelming number of circuit simulations to arrive at an optimized sizing result. On the other hand, many published manual sizing methods by using the conventional device equations also require repeated SPICE simulations to correct the equation-based sizing results. This paper proposes a systematic gm/ID-based initial sizing method specifically customized for designing multiple-stage operational amplifiers (Op Amps). A main feature of the proposal is to use circuit-level design equations as constraints on the gm/ID table lookup method to substantially reduce the uncertainty in the sizing calculations. As a result, a significant amount of SPICE based correction work can be reduced to complete an initial sizing. The proposed sizing procedure includes a few regular sizing rules customized to the configuration of multi-stage Op Amps. We validate the proposed sizing method by application to several multi-stage Op Amp examples with a capacitive load or Miller compensation. Simulations have justified that the produced initial sizing results can achieve most of the prespecified design targets. 相似文献
2.
The present research included two field studies investigating, firstly, the effects of round and angular typefaces on taste expectations and, secondly, how such expectations may have downstream effects on naturalistic consumer choice. A taste experiment conducted at a science festival asked participants (N = 125) to rate the expected and actual sweetness and sourness of beer served from plastic cups labelled with either angular or round typeface. Effects of typeface were found on both taste expectations and perceived taste, but in opposite directions; participants rated the expected sourness of a beer as higher in the round (vs. angular) typeface condition, whereas they rated perceived sourness as lower in the round compared to the angular typeface condition. A follow-up field study conducted at a beer bar tested whether different typefaces on a beer board would affect actual beer choices. Data consisted of beer transactions (N = 1,952) and included the monetary amount, and the specific style, and size of beer purchased. The results showed that average transaction amount was lower in the round (vs. angular) typeface condition, and that customers purchased more sour beer options in this condition. These findings support a crossmodal compensation account, and suggest that round typefaces could increase choices of contrasting sour products. Hence, marketers may want to consider how typefaces can either enhance or diminish certain tastes. 相似文献
3.
4.
This paper investigates the prescribed performance attitude control problem for flexible spacecraft subject to external disturbances and actuator constraints. By using a new performance function and an error transformation, the attitude control system is transformed into an error system which will be kept bounded to ensure expected dynamic and steady-state responses. Compared with the commonly used performance function, the modified one has an explicit prespecified terminal time which determines the maximum convergence time of the attitude control system. A modal observer and a disturbance observer are designed to deal with the flexible vibration and disturbances, respectively. Furthermore, when considering actuator saturation, an improved control strategy is developed with an auxiliary system utilized to compensate the saturation. The stability of the closed-loop system is analyzed by Lyapunov theory. Simulation results show the effectiveness and performance of the proposed methods. 相似文献
5.
针对运动强反光体表面温度实时测量困难、精度低这一难点,本文从红外测温原理入手,分析并揭示了红外测温精度易受到被测物体反射率、测量距离、测量环境、红外入射角等因素的影响。根据铝板材加工设备轧辊表面测温实际需要设计了一种利用红外传感器实现对强反光体表面温度点对点测量的方案。通过对测量数据的研究分析建立了一种基于斯忒藩定律的红外入射角度补偿算法,以此减小因红外入射角度变化产生的测温误差。实验结果证明本方法能较好地弥补红外入射角度变化产生的测温误差,提高测温精度。该补偿算法运算简单,适应性强,为改善入射角度变化对测温精度影响提供了新的方法。 相似文献
6.
《Mechatronics》2021
Producing a stable and agile bionic eye for visual image acquisition in robotics is a challenging task. In this paper, we design a bionic eye with mirror-symmetric distribution and cross-connection of flexible ropes. This mechanism is based on oculomotor law and the physiological structure of the extraocular muscles (EOMs). Specifically, the basic structural parameters are determined by Listing’s law, and the unique connection of the flexible ropes can realize the functions of the recti and oblique muscles. Furthermore, to mimic the trochlea structure, a pulley mechanism is constructed to permit the free movement of the flexible ropes. Through simulation and physical experiments, it is demonstrated that the bionic eye mechanism can move with agility under the structural parameters. The experimental results indicate that the proposed bionic eye mechanism has a superior motion accuracy of 2.798 mm, which is 6.7% of the maximum motion distance, and the repeatable accuracy of the mechanism can up to 0.210 mm. 相似文献
7.
Adam S. Wilk Zhaoli Tang Courtney Hoge Laura C. Plantinga Janice P. Lea 《Hemodialysis international. International Symposium on Home Hemodialysis》2019,23(4):479-485
Introduction: Compared to traditional in‐center hemodialysis (HD), in‐center nocturnal dialysis (INHD) is characterized by longer sessions and nighttime administration, which may lead to better outcomes for some patients. Given the importance of patient choice in the decision to initiate INHD, we explored associations between patients’ psychosocial characteristics and their receipt of INHD. Methods: Among hemodialysis patients at a medium‐sized dialysis organization, we identified INHD patients as those for whom ≥80% of dialysis sessions were INHD sessions—starting at 6:30 pm or later and lasting ≥5 hours—over the 3 months (≥20 sessions total) after their first INHD session. We extracted dialysis session data from electronic medical records and psychosocial data from social worker assessments. We tested associations of patients’ psychosocial characteristics—as well as demographic and clinical characteristics—with INHD receipt among all hemodialysis patients (INHD and HD) in bivariate analyses and multivariable logistic regression models. Findings: Among 759 patients with complete data, we identified 47 (6.2%) as INHD patients. On average, these patients were more likely than HD patients to be employed (full‐time 10.6% vs. 5.2%; part‐time 17.0% vs. 4.2%; P < 0.001), and they were significantly less likely to require ambulatory assistance (14.9% vs. 39.6%, P < 0.001). In multivariable regressions, we found that part‐time employment (versus being unemployed) was associated with a 7.1 percentage‐point higher likelihood of being an INHD patient (P = 0.01), and the negative association with ambulatory assistance needs approached statistical significance (P = 0.056). No other psychosocial factors included in this main regression analysis were statistically significantly associated with INHD patient status. Discussion: Researchers comparing the outcomes of patients undergoing INHD versus other treatment modalities will need to account for differences in employment status—and other factors like requiring ambulatory assistance and age which may predict the ability to work—between INHD users and comparison patients to avoid bias in estimates. 相似文献
8.
《Contact lens & anterior eye》2019,42(4):373-379
PurposeTo gain a better understanding of eye care professionals’ (ECPs) perceptions regarding the benefits of silicone hydrogel (SiH) daily disposable contact lenses (DDCL), particularly with respect to health, comfort and patient satisfaction.MethodsA survey was conducted with 300 ECPs in the United States, United Kingdom and Japan during November 2017. The survey comprised 34 statements relating to SiH DDCLs, to which the ECPs provided their level of agreement using a 6 point Likert scale. A minimum of 70% agreement was set to define majority agreement. Categories of statements included Health, Comfort, Patient Experience, and Standard of Care.ResultsECPs rated the highest levels of agreement to perceptions within the Patient Experiences and Health categories. The six statements receiving the highest ratings were “Silicone hydrogel 1 day lenses satisfy today’s patients’ demanding lifestyles” (93% agreement); “Silicone hydrogel 1 day lenses are the best choice to safeguard my patients’ eye health related to contact lens wear” (92%); “Silicone hydrogel 1 day lenses provide the best benefits to my patients” (92%); “Silicone hydrogel 1 day lenses provide better long term eye health for my patients than hydrogel 1 day lenses” (91%); “Silicone hydrogel is the healthiest lens material for my daily disposable patients” (90%); and “Silicone hydrogel 1 day lenses provide a better wearing experience for my patients than hydrogel 1 day lenses” (90%).ConclusionECPs perceive that SiH DDCLs offer long-term eye health and comfort for the patient and although the ECPs surveyed would not necessarily prescribe SiH DDCLs to all their patients, they would prescribe them to most of their patients. The results support the premise that while ECPs consider SiH 1 day contact lenses as the current “standard of care”; the principal barrier continues to be the perceived higher cost of these lenses. 相似文献
9.
The approach power compensator system (APCS) plays a role in the automatic carrier landing system (ACLS), and the performance of the APCS is affected
by the carrier air-wake in the final-approach . In this paper, the importance of the APCS is verified through the analysis of the signal flow chart of the ACLS.
Hence, it is necessary to suppress the carrier air-wake in order to improve the anti-interference ability. The adaptive sliding mode control (ASMC) not only
has better dynamic tracking performance compared to the nonlinear mode, but also can efficiently resist the disturbance caused by the carrier air-wake.
The design of the longitudinal control law of the ACLS is based on the carrier-based aircraft nonlinear model and the carrier air-wake model. It comprises
the longitudinal guidance rate, autopilot (CAS) and the APCS. The ASMC is used to design the APCS to suppress the carrier air-wake. A comparison of the
simulation results indicates that the design based on the ASMC has better anti-interference ability and can keep the velocity constant on the timely. 相似文献
10.
针对雷达天线罩瞄准误差的补偿问题,提出了一种适用于各向同性的天线罩瞄准误差修正方法。构建了基于一维物理光学法的天线罩瞄准误差的数学模型,推导了雷达导引头测量目标角度和角速度的误差修正公式。试验结果表明,该方法有效降低了天线罩瞄准误差对目标角速度性能的影响。 相似文献