Large Scale Signal and Interconnect FDTD Modeling for BGA Package

This paper introduces a Finite-Difference Time-Domain (FDTD) approach to modeling portions of Ball Grid Array (BGA) package interconnect circuits. A fullwave circuit model including vias, trace segments, and ground vias was generated, using a computer gridding tool, and fed into the FDTD (Taflove and Hagness, 2005) program. The simulated results were correlated with TDR measurements

Inter-group alliance dynamics in Indo-Pacific bottlenose dolphins (Tursiops aduncus)

The social intelligence hypothesis holds that complex social relationships are the major selective force underlying the evolution of large brain size and intelligence. Complex social relationships are exemplified by coalitions and alliances that are mediated by affiliative behavior, resulting in differentiated but shifting relationships. Male Indo-Pacific bottlenose dolphins in Shark Bay, Australia, form three alliance levels or ‘orders’, primarily among non-relatives. Strategic alliance formation has been documented within both first- and second-order alliances and between second-order alliances (‘third-order alliances’), revealing that the formation of strategic inter-group alliances is not limited to humans. Here we conducted a fine-scale study on 22 adult males over a 6-year period to determine if third-order alliance relationships are differentiated, and mediated by affiliative interactions. We found third-order alliance relationships were strongly differentiated, with key individuals playing a disproportionate role in maintaining alliances. Nonetheless, affiliative interactions occurred broadly between third-order allies, indicating males maintain bonds with third-order allies of varying strength. We also documented a shift in relationships and formation of a new third-order alliance. These findings further our understanding of dolphin alliance dynamics and provide evidence that strategic alliance formation is found in all three alliance levels, a phenomenon with no peer among non-human animals

Early Time Charge Replenishment of the Power Delivery Network in Multi-Layer PCBs

The investigation of decoupling issues has been extensively treated in the literature in both the frequency and the time domain [1-9]. The two domains describe from different perspectives the same physical phenomenon, being related by a Fourier transform. In this article, well known decoupling issues usually addressed in the frequency domain [1,2] are discussed in the time domain. Moreover, some modeling issues related to the cavity model approach are discussed and, in particular, the circuit extraction feature associated with this methodology is utilized throughout the article to carry out the time domain simulations within a SPICE based-tool. The depletion of charges stored between the power bus is investigated in the time domain as a function of the plane thickness, SMT decoupling closeness and interconnect inductance values

Comparison of Via Equivalent Circuit Model Accuracy using Quasi-Static and Full-Wave Approaches

The EMC and signal integrity impact of printed circuit board (PCB) trace discontinuities, such as vias, where the signal is transitioned from one layer to another in the PCB stackup, have become significant recently with the use of very high speed signals in today\u27\u27s systems. If these discontinuities are ignored, significant distortion of the high speed signal can occur, and in many cases, cause data errors. A fast and accurate technique to include the effect of via discontinuities in the typical design process is needed to ensure this distortion is considered if significant. Therefore, a simple equivalent circuit for the via discontinuity is needed so that this equivalent circuit can be easily used in the normal signal integrity analysis tools. This paper demonstrates the effect on the equivalent circuit values as the distance between the signal via and the return-current via is increased. Also, the frequency range where a quasi-static based equivalent circuit is accurate or where a full-wave model is required is shown for the various distances between vias

Validity and reliability of a wearable inertial sensor to measure velocity and power in the back squat and bench press

Orange, ST, Metcalfe, JW, Liefeith, A, Marshall, P, Madden, LA, Fewster, CR, and Vince, RV. Validity and reliability of a wearable inertial sensor to measure velocity and power in the back squat and bench press. J Strength Cond Res 33(9): 2398-2408, 2019-This study examined the validity and reliability of a wearable inertial sensor to measure velocity and power in the free-weight back squat and bench press. Twenty-nine youth rugby league players (18 ± 1 years) completed 2 test-retest sessions for the back squat followed by 2 test-retest sessions for the bench press. Repetitions were performed at 20, 40, 60, 80, and 90% of 1 repetition maximum (1RM) with mean velocity, peak velocity, mean power (MP), and peak power (PP) simultaneously measured using an inertial sensor (PUSH) and a linear position transducer (GymAware PowerTool). The PUSH demonstrated good validity (Pearson's product-moment correlation coefficient [r]) and reliability (intraclass correlation coefficient [ICC]) only for measurements of MP (r = 0.91; ICC = 0.83) and PP (r = 0.90; ICC = 0.80) at 20% of 1RM in the back squat. However, it may be more appropriate for athletes to jump off the ground with this load to optimize power output. Further research should therefore evaluate the usability of inertial sensors in the jump squat exercise. In the bench press, good validity and reliability were evident only for the measurement of MP at 40% of 1RM (r = 0.89; ICC = 0.83). The PUSH was unable to provide a valid and reliable estimate of any other criterion variable in either exercise. Practitioners must be cognizant of the measurement error when using inertial sensor technology to quantify velocity and power during resistance training, particularly with loads other than 20% of 1RM in the back squat and 40% of 1RM in the bench press

Noise Coupling Between Power/Ground Nets Due to Differential Vias Transitions in a Multilayer PCB

Due to the increase in board density, routing traces on different layers becomes a widely used strategy. Through-hole vias are often used to connect these traces. Those vias that penetrate power/ground plane pairs could cause noise coupling between signal and power/ground nets. At the same time, the need for clean signal transmitted to receivers results in a wide use of differential signals. This paper studies the noise coupling mechanism caused by a differential pair of vias penetrating power/ground plane pair using a physics-based via-plane model combined with transmission line models for traces. A 26-layer printed circuit board with a pair of differential vias have been modeled. The simulated results clearly demonstrate the impact of ground vias and via stubs on noise coupling

A Circuit Approach to Model Narrow Slot Structures in a Power Bus

A coupled transmission line model for narrow slot structures in DC power planes is proposed. This approach, combined with SPICE-based cavity models and a segmentation method, provides an easy and fast way to model relatively complex structures of power planes with narrow slots often used for isolation purposes. This approach is used to achieve isolation using gapping. The cavity model formulations for rectangular and isosceles right triangular segments are reviewed. The rationale of modeling the narrow slot as a three-conductor transmission line is described. The modeling results are shown and compared with the output of a full wave simulation tool, HFSS, and with experimental measurements

Validation of Equivalent Circuits Extracted from S-Parameter Data for Eye-pattern Evaluation

S-parameter circuit model extraction is usually characterized by a trade off between accuracy and complexity. Trading one feature for another may or may not affect the goodness of the reconstructed S-parameter data, which are obtained from frequency domain simulations of the models extracted. However, the ultimate test for the validity of these equivalent circuit representations should be left to eye-diagram simulations, which provide useful insights, from an SI point of view, about the degradation of the signal, as it travels through the system. Physics based simplication procedures can be used to tune the models and achieve less complexity, whereas the comparisons of the eye-diagrams may help to quantify the goodness of an these circuits extracted. In fact, the most accurate model is not necessary the best to be used

Voltage Regulator Module Noise Analysis for High-Volume Server Applications

This paper presents a methodology to analyze voltage regulator module (VRM) noise coupling problems in high-volume server applications. The technique is applied on a real engineering design. The comprehensive model includes irregular power shapes, decoupling capacitors, and dielectric and conductive loss. Irregular shaped power plane modeling is cross-checked with four separate methods to demonstrate accuracy

Methamphetamine Use and Emergency Department Utilization: 20 Years Later

Background. Methamphetamine (MAP) users present to the emergency department (ED) for myriad reasons, including trauma, chest pain, and psychosis. The purpose of this study is to determine how their prevalence, demographics, and resource utilization have changed. Methods. Retrospective review of MAP patients over 3 months in 2016. Demographics, mode of arrival, presenting complaints, disposition, and concomitant cocaine/ethanol use were compared to a 1996 study at the same ED. Results. 638 MAP-positive patients, 3,013 toxicology screens, and 20,203 ED visits represented an increase in prevalence compared to 1996: 461 MAP-positive patients, 3,102 screens, and 32,156 visits. MAP patients were older compared to the past. Mode of arrival was most frequently by ambulance but at a lower proportion than 1996, as was the proportion of MAP patients with positive cocaine toxicology screens and ethanol coingestion. Admission rate was lower compared to the past, as was discharge to jail. The proportion of MAP patients presenting with blunt trauma was lower compared to the past and higher for chest pain. Conclusion. A significant increase in the prevalence of MAP-positive patients was found. Differences in presenting complaints and resource utilization may reflect the shifting demographics of MAP users, as highlighted by an older patient population relative to the past