6,443 research outputs found
Modelling delay and noise in arbitrarily coupled RC trees.
No full textClosed-form equations for second-order transfer functions of general arbitrarily coupled resistance-capacitance (RC) trees with multiple drivers are reported. The models allow precise delay and noise calculations for systems of coupled interconnects with guaranteed stability and represent the minimum complexity associated with this class of circuits. Their accuracy is extensively compared against other relevant models and is found to be better or comparable to more expensive models. All results are derived from a theoretical approach, and their physical basis is examined. The simplicity, accuracy, and generality of the models make them suitable for use in early signal integrity analyses of complex systems and incremental physical optimization
Supplemental Material, Chi-RC-QOL_questionnaire_(JOTR)_1_-_Appendix - Chinese version of the Rotator Cuff Quality of Life questionnaire: Cross-cultural adaptation and validation in rotator cuff-impaired patients in Hong Kong
No full textSupplemental Material, Chi-RC-QOL_questionnaire_(JOTR)_1_-_Appendix for Chinese version of the Rotator Cuff Quality of Life questionnaire: Cross-cultural adaptation and validation in rotator cuff-impaired patients in Hong Kong by Ho-ming Li, Jackie YM Chau, SB Woo, J Lai and WL Chan in Journal of Orthopaedics, Trauma and Rehabilitation</p
HIV and tuberculosis in Ho Chi Minh City, Vietnam, 1997-2002.
No full textIn Ho Chi Minh City, Vietnam, reporting rates for tuberculosis (TB) are rising in an emerging HIV epidemic. To describe the HIV epidemic among TB patients and quantify its impact on rates of reported TB, we performed a repeated cross-sectional survey from 1997 through 2002 in a randomly selected sample of inner city TB patients. We assessed effect by adjusting TB case reporting rates by the fraction of TB cases attributable to HIV infection. HIV prevalence in TB patients rose exponentially from 1.5% to 9.0% during the study period. Young (<35 years), single, male patients were mostly affected; injection drug use was a potent risk factor. After correction for HIV infection, the trend in TB reporting rates changed from a 1.9% increase to a 0.4% decrease per year. An emerging HIV epidemic, concentrated in young, male, injection drug users, is responsible for increased TB reporting rates in urban Vietnam
A Compact 10-MHz RC Frequency Reference With a Versatile Temperature Compensation Scheme
No full textThis article presents the design and implementation of a compact CMOS RC frequency reference. It consists of a frequency-locked loop (FLL) that locks the period of a voltage-controlled oscillator (VCO) to the time an RC network takes to charge to a reference voltage. Conventionally, an RC time constant with a near-zero temperature coefficient (TC) is realized by using a trimmed network of resistors with different TCs. In this work, such a network is used to realize a temperature-dependent reference voltage whose TC cancels that of a single-resistor RC time constant. Compared with the conventional approach, which requires resistors with TCs of opposite polarity, the proposed approach can be implemented with resistors with TCs of similar polarity, and so it can be implemented in most CMOS processes. To compensate for RC spread, a trimmed capacitor is used to adjust the nominal frequency. Two prototype chips were made, one based on p- /n-polysilicon resistors and other based on silicided/p-diffusion resistors. Fabricated in a standard 180-nm CMOS technology, the polysilicon-based prototype has an active area of 0.01 mm2 and an absolute inaccuracy of ±2800 ppm from -45 °C to 125 °C with a fixed TC-trim and a one-point frequency trim. After one week of accelerated aging at 150 °C, however, significant drift (5000 ppm) was observed. The diffusion-based prototype exhibits greater inaccuracy (±14 400 ppm) but much less drift (600 ppm).Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
HO-1 is a favorable prognostic factor for HBV-HCC patients who underwent hepatectomy
No full textChun-Nan Yeh,1 Ren-Chin Wu,2 Chi-Tung Cheng,1 Chun-Yi Tsai,1 Yau-Ren Chang,1 Ta-Sen Yeh,1 Tsung-Han Wu,1 Wei-Chen Lee,1 Kun-Chun Chiang3 1Department of Surgery, Liver Research Center, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan 333, Taiwan; 2Department of Pathology, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan 333, Taiwan; 3General Surgery Department, Chang Gung Memorial Hospital, Chang Gung University, Keelung, Taiwan Background: More than 500,000 people suffered from hepatocelluar carcinoma (HCC) annually and the relative incidence to mortality rate indicates its unfavorable prognosis. Several studies have proved that heme-oxygenase-1 (HO-1) is indirectly engaged in the invasion and the metastasis of some types of malignancies, including breast cancer, prostate cancer, and lung cancer. The role of HO-1 in hepatitis B virus (HBV)-related HCC is still not clarified.Materials and methods: The Western blot, doubling time, cell cycle analysis, migration assay, invasion assay, gene transfection, xenograft animal model, immunohistochemistry staining, and clinical validation study were applied in this study.Results: HO-1 overexpression not only decreased the growth but also inhibited the migration and invasion in human HBV-HCC cells (Hep-3B vs PLC/PRF/5 ). The inhibitory effect on growth, migration, and invasion is further demonstrated by the overexpression of HO-1 in Hep-3B cell by transfection study. Furthermore, HO-1 decreasing the growth of HBV-HCC was confirmed in animal study. The clinical validation illustrated that higher HO1 expression was also associated with favorable disease-free survival of HBV-HCC patients who underwent hepatectomy.Conclusions: We identified HO-1 as a favorable prognostic factor for HBV-HCC patients who underwent hepatectomy. Keywords: HO-1, HBV, HCC, hepatectom
A CMOS Dual-RC frequency reference with ±250ppm inaccuracy from -45°C to 85°C
No full textTo comply with wired communication standards such as USB, SATA and PCI/PCI-E, systems-on-chip require frequency references with better than 300ppm accuracy. LC-based references achieve 100ppm accuracy [1], but suffer from high power consumption (∼20mW). Thermal diffusivity (TD) references require less power (∼2mW), at the expense of less accuracy (1000ppm) [2]. RC-based references offer the lowest power consumption, but their accuracy is typically limited to ∼0.1% [3]. In RC relaxation oscillators, comparator offset and delay are the major sources of inaccuracy [4,5]. References based on frequency-locked loops (FLLs) circumvent these by locking an oscillator's frequency to the time-constant of an RC filter, but their accuracy is then limited by the nonlinear temperature dependency of on-chip resistors [3,6].Session 3.3 Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Instrumentation(OLD)Applied Quantum ArchitecturesMicroelectronic
Inhibition zone diameter measurement (mm) in <i>Candida</i> spp., <i>Aggregatibacter actinomycetemcomitans</i>, <i>Staphylococcus aureus</i>, and <i>Pseudomonas aeruginosa</i> by Hinora<sup>®</sup> (HO) and Refrecare<sup>®</sup> (RC).
No full textInhibition zone diameter measurement (mm) in Candida spp., Aggregatibacter actinomycetemcomitans, Staphylococcus aureus, and Pseudomonas aeruginosa by Hinora® (HO) and Refrecare® (RC).</p
Experimental and theoretical investigation of crack width calculation methods for RC ties
No full textThis paper theoretically and experimentally investigates the semi-empirical formulas recommended by Eurocode 2 (EC2), fib Model Code 2010 (MC2010), and Eurocode 2 with the German National Annex (DIN) for calculating crack widths in reinforced concrete. It is shown that the formulas can be derived from the principles for the idealized behavior of RC ties. However, instead of explicitly solving the resulting differential equations, the use of simplifications leads to inconsistent formulas. An experimental study was carried out involving the testing of eight RC ties to discover the modeling uncertainty of the formulas. It was found that EC2 substantially overestimated the crack widths for the RC ties. MC2010 and DIN seemed to predict the crack widths better, but gave rather a large number of nonconservative crack width predictions. These experimental results, combined with the theoretical study, suggest that a more consistent calculation model should be formulated by explicitly solving the resulting differential equation.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Applied Mechanic
RC SMOOTHING OF SPECTRA
No full textAuthor Institution: Department of Physics, Michigan State University East LansingBy convoluting an exponential function with calculated spectra consisting of single and multiple sets of lines of various widths and line shapes, we have determined the effects that time constant (RC) has on recorded spectra. For equivalent experiments, in which the scanning rates d/dt are equal, we have concluded that the optimum value of RC is essentially independent of whether the spectrum is to be digitized or not, and independent of the sampling rate if digitization is used. A trade-off among the desirable and undesirable effects of RC leads us to recommend a value of RC about one-tenth of the full width at half height of the sharpest individual lines in the observed spectrum. This research was supported by a grant from the National Science Foundation
Effects of Reinforcement on Ballistic Resistance of RC Targets
No full textReinforced concrete (RC) is a widely used construction material, renowned for its high strength and durability. Despite this, when subjected to high-velocity impacts, such as those from ballistic projectiles or blast loading, RC structures are prone to local failure. This can significantly damage their structural integrity, potentially leading to total failure. Therefore, understanding the failure behavior of RC structures under such impact loads is of critical importance.
The rebar ratio is one of the factors that affect the erosion behavior of RC targets. The rebar ratio refers to the proportion of rebar (reinforcing steel) in the RC target relative to the concrete. A higher rebar ratio is expected to result in higher resistance to local failure, as the rebar provides additional reinforcement to the concrete. The hardness of the projectile is another factor that affects the failure behavior of RC targets. An ogive-nose steel projectile is expected to cause more profound local failure than a soft-type projectile, as a projectile is a relatively minor projectile deformation after a collision.
In this study, a series of impact tests were performed on RC targets with different rebar ratios and impact velocities using ogive-nose steel projectile. The penetration depth, scabbing& perforation limit were measured and analyzed as a function of the rebar ratio and impact velocity. The accuracy of existing empirical formulae recommended by various design standards for military and nuclear structures was verified using the results, and a modified empirical formula for predicting the penetration depth of RC targets subjected to impact loading was developed.
A total of 21 RC targets were tested in this study, with four different rebar ratios (0%, 1.6%, 2.5%, and 3.4%) and a constant target size of 600mm x 600mm x 500mm. The targets were made of normal-weight concrete with a compressive strength of 52 MPa. The rebar was made of high-strength steel with a yield strength of 470 MPa.
The impact tests were performed using a 60 mm single-stage gas gun in EPTC, in which an ogive-nose steel projectile was launched through helium gas pressure and collided with the RC target at the target speed. The impact velocity was varied from 550m/s to 850m/s in increments of 50m/s. The penetration depth, scabbing& perforation limit was measured after each impact test and recorded for analysis.
The results showed that the rebar ratio sig the local failure behavior of the RC targets. The targets with a higher rebar ratio (2.5% and 3.4%) showed less erosion than those with a lower rebar ratio (0% and 1.6%). The results also showed that the impact velocity sig the failure of the RC target, with higher impact velocities resulting in higher impact damage.
Based on the results, a modified empirical formula was suggested for predicting the impact damage of RC targets subjected to impact loading. The formula takes into account both the rebar ratio and impact velocity. Then, the validity of the proposed formula was verified by applying it to the existing experimental data of 153ea and FEA using the LS-Dyna program.
In conclusion, this study has investigated the impact response of reinforced concrete (RC) targets under various loading conditions, including different rebar ratios and striking velocities. The results have shown that the rebar ratio can significantly impact the RC target's response to impact loading. The modified empirical formula developed in this study provides a valuable tool for predicting the response of RC targets to impact loading. It can inform design and engineering decisions related to impact resistance.
Future work in this area could include further testing with a larger number of RC target specimens and developing more detailed numerical models better to understand the mechanisms of impact damage in RC targets. Additionally, it may be helpful to investigate the impact response of RC targets under more realistic loading conditions, such as those that incorporate dynamic loading and material nonlinearities.
Overall, this study has contributed to a deeper understanding of the impact response of RC targets and has provided valuable insights into the factors that can affect this response. This study's findings can inform the design and engineering of structures subjected to impact loading and ensure that these structures are adequately protected against impact damage.1. Introduction 1
1.1. Research background 1
1.2. Research objectives and scope 10
1.3. Organization 12
2. Literature Review 14
2.1. Introduction 14
2.2. Design codes & guideline for local effect 15
2.2.1. Military design codes & guidelines 15
2.2.2. NPP design codes & guidelines 17
2.3. Existing empirical formulae 18
2.3.1. Modified Petry formula 21
2.3.2. Ballistic Research Laboratory (BRL) formula 22
2.3.3. Army corps of engineers (ACE) formula 22
2.3.4. Modified NDRC formula 23
2.3.5. Kar formula 25
2.3.6. CEA-EDF formula 26
2.3.7. UKAEA formula 27
2.3.8. Bechtel formula 29
2.3.9. Stone and Webster formula 29
2.3.10. Degen formula 30
2.3.11. Haldar-Hamieh formula 30
2.3.12. Adeli-Amin formula 31
2.3.13. Hughes formula 32
2.3.14. CRIEPI formula 34
2.3.15. Conwep formula 35
2.4. Existing analytical formulae 36
2.4.1. Dynamic cavity expansion theory for concrete material 36
2.4.1.1. Plastic region 38
2.4.1.2. Cracked-elastic region 41
2.4.1.3. Inverse calculation procedure 45
2.4.1.4. Results of the previous studies 46
2.5. Concluding remarks 48
3. Impact Test 49
3.1. Introduction 49
3.2. Test variables 50
3.2.1. Projectile preparation 53
3.2.2. Specimen preparation 57
3.3. Material tests 63
3.3.1. Concrete 63
3.3.2. Reinforcing steel bars 67
3.4. Test procedures 69
3.4.1. Test setup 69
3.4.2. Measurement and data acquisition 72
3.4.2.1 Impact and residual velocity 72
3.4.2.2. Failure mode and penetration depth 77
3.4.2.3. Mass of specimen 82
3.4.2.4. Mass and length of projectile 83
3.4.2.5. Strain of rebar 84
3.5. Concluding remarks 86
4. Test results and discussion 87
4.1. Introduction 87
4.2. Damage assessment 90
4.2.1. Failure mode 90
4.2.2. Mass loss of specimen 97
4.2.3. Mass and length loss of projectile 99
4.3. Assessment of penetration depth 103
4.4. Assessment of scabbing & perforation limit 108
4.5. Effect of reinforcement on impact resistance 111
4.6. Modification of empirical formula 115
4.6.1. Suggestion of modified impact formula 115
4.6.2. Verification of developed impact formula 119
4.7. Concluding remarks 124
5. Analytical Study 126
5.1. Introduction 126
5.2. Description of impact test for RC target 127
5.2.1. Modeling details 127
5.2.2. Material model for concrete 129
5.2.3. Material model for reinforcing steel 135
5.2.4. Material model for projectile 136
5.2.5. Data acquisition 137
5.3. Numerical analysis results 138
5.3.1. Overview of FEA analysis 138
5.3.2. Effect of reinforcement 143
5.4. Concluding Remarks 146
6. Conclusion 147
6.1. Summary and major findings of this study 147
6.2. Recommendations for further studies 149
Reference 151
Appendix A 159
Appendix B 163
Appendix C 170
국문초록 190Docto
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