Physics-based passivity-preserving parameterized model order reduction for PEEC circuit analysis

The decrease of integrated circuit feature size and the increase of operating frequencies require 3-D electromagnetic methods, such as the partial element equivalent circuit (PEEC) method, for the analysis and design of high-speed circuits. Very large systems of equations are often produced by 3-D electromagnetic methods, and model order reduction (MOR) methods have proven to be very effective in combating such high complexity. During the circuit synthesis of large-scale digital or analog applications, it is important to predict the response of the circuit under study as a function of design parameters such as geometrical and substrate features. Traditional MOR techniques perform order reduction only with respect to frequency, and therefore the computation of a new electromagnetic model and the corresponding reduced model are needed each time a design parameter is modified, reducing the CPU efficiency. Parameterized model order reduction (PMOR) methods become necessary to reduce large systems of equations with respect to frequency and other design parameters of the circuit, such as geometrical layout or substrate characteristics. We propose a novel PMOR technique applicable to PEEC analysis which is based on a parameterization process of matrices generated by the PEEC method and the projection subspace generated by a passivity-preserving MOR method. The proposed PMOR technique guarantees overall stability and passivity of parameterized reduced order models over a user-defined range of design parameter values. Pertinent numerical examples validate the proposed PMOR approach

Interpolation-based parameterized model order reduction of delayed systems

Three-dimensional electromagnetic methods are fundamental tools for the analysis and design of high-speed systems. These methods often generate large systems of equations, and model order reduction (MOR) methods are used to reduce such a high complexity. When the geometric dimensions become electrically large or signal waveform rise times decrease, time delays must be included in the modeling. Design space optimization and exploration are usually performed during a typical design process that consequently requires repeated simulations for different design parameter values. Efficient performing of these design activities calls for parameterized model order reduction (PMOR) methods, which are able to reduce large systems of equations with respect to frequency and other design parameters of the circuit, such as layout or substrate features. We propose a novel PMOR method for neutral delayed differential systems, which is based on an efficient and reliable combination of univariate model order reduction methods, a procedure to find scaling and frequency shifting coefficients and positive interpolation schemes. The proposed scaling and frequency shifting coefficients enhance and improve the modeling capability of standard positive interpolation schemes and allow accurate modeling of highly dynamic systems with a limited amount of initial univariate models in the design space. The proposed method is able to provide parameterized reduced order models passive by construction over the design space of interest. Pertinent numerical examples validate the proposed PMOR approach

Reduced order modeling of delayed PEEC circuits

We propose a novel model order reduction technique that is able to accurately reduce electrically large systems with delay elements, which can be described by means of neutral delayed differential equations. It is based on an adaptive multipoint expansion and model order reduction of equivalent first order systems. The neutral delayed differential formulation is preserved in the reduced model. Pertinent numerical results validate the proposed model order reduction approach

Multipoint model order reduction of delayed PEEC systems

We present a new model order reduction technique for electrically large systems with delay elements, which can be modeled by means of neutral delayed differential equations. An adaptive multipoint expansion and model order reduction of equivalent first order systems are combined in the new proposed method that preserves the neutral delayed differential formulation. An adaptive algorithm to select the expansion points is presented. The proposed model order reduction technique is validated by pertinent numerical results. A comparison with a previous model order reduction algorithm based on a single point expansion is performed to show the considerably improved modeling capability of the new proposed technique

Deformed Pleistocene marine terraces along the Ionian sea margin of southern Italy: unveiling blind fault-related folds contribution to coastal uplift

Morphotectonic analysis and fault numeric modeling of uplifted marine terraces along the Ionian Sea coast of the Southern Apennines allowed us to place quantitative constraints on middle Pleistocene-Holocene deformation. Ten terrace orders uplifted to as much as +660 m were mapped along ~80 km of the Taranto Gulf coastline. The shorelines document both a regional and a local, fault-induced contribution to uplift. The intermingling between the two deformation sources is attested by three 10 km scale undulations superimposed on a 100 km scale northeastward tilt. The undulations spatially coincide with the trace of NW-SE striking transpressional faults that affected the coastal range during the early Pleistocene. To test whether fault activity continued to the present, we modeled the differential uplift of marine terraces as progressive elastic displacement above blind oblique-thrust ramps seated beneath the coast. Through an iterative and mathematically based procedure, we defined the best geometric and kinematic fault parameters as well as the number and position of fault segments. Fault numerical models predict two fault-propagation folds cored by blind thrusts with slip rates ranging from 0.5 to 0.7 mm/yr and capable of generating an earthquake with a maximum moment magnitude of 5.9–6.3. Notably, we find that the locus of predominant activity has repeatedly shifted between the two fault systems during time and that slip rates on each fault have temporally changed. It is not clear if the active deformation is seismogenic or dominated by aseismic creep; however, the modeled faults are embedded in an offshore transpressional belt that may have sourced historical earthquakes

First Steps in Air Quality for Built Environment Practitioners

Air pollution is the biggest environmental risk to health. Globally, nine out of ten people live in a city that does not comply with WHO air quality standards. Within the UK, poor outdoor air quality is linked to 50,000 deaths each year. The most vulnerable are children, the elderly, or those with pre-existing medical conditions. The design of our urban infrastructure 13 including Green Infrastructure (GI) such as trees, parks, and green walls 13 determines where air pollution is produced, and how it disperses. Built environment professionals should consider air quality at all stages of urban design and development

First Steps in Air Quality for Built Environment Practitioners

Air pollution is the biggest environmental risk to health. Globally, nine out of ten people live in a city that does not comply with WHO air quality standards. Within the UK, poor outdoor air quality is linked to 50,000 deaths each year. The most vulnerable are children, the elderly, or those with pre-existing medical conditions. The design of our urban infrastructure 13 including Green Infrastructure (GI) such as trees, parks, and green walls 13 determines where air pollution is produced, and how it disperses. Built environment professionals should consider air quality at all stages of urban design and development

PEEK versus metal cages in posterior lumbar interbody fusion: a clinical and radiological comparative study

Background: Low back pain and sciatica represent a common disabling condition with a significant impact on the social, working and economic lives of patients. Transforaminal lumbar interbody fusion (TLIF) is a surgical procedure used in degenerative spine conditions. Several types of cages were used in the TLIF procedure. Purpose: To determine whether there is a difference in terms of symptomatology improvement, return to daily activities and fusion rate between metal cages and polyetheretherketone (PEEK) cages. Methods: We have retrospectively reviewed 40 patients who have undergone TLIF from October 2015 to May 2016. All patients were clinically evaluated with questionnaires and were assessed with CT scan and standing X-ray films of the full-length spine. Results: We found no significant functional differences in the two groups. At 1-year follow-up, osteolysis was present in 50% of cases of the PEEK cages and in 10% cases of the metal cages. The degree of fusion at 1 year was evaluated as complete in 40% cases of the metal cages and 15% cases of the PEEK cages. Conclusions: We have found a better fusion rate and prevalence of fusion in the group treated with metal cages, reflecting the well-known osteoinductive properties of titanium and tantalum

First Steps in Air Quality for Built Environment Practitioners

Air pollution is the biggest environmental risk to health. Globally, nine out of ten people live in a city that does not comply with WHO air quality standards. Within the UK, poor outdoor air quality is linked to 50,000 deaths each year. The most vulnerable are children, the elderly, or those with pre-existing medical conditions. The design of our urban infrastructure – including Green Infrastructure (GI) such as trees, parks, and green walls – determines where air pollution is produced, and how it disperses. Built environment professionals should consider air quality at all stages of urban design and development

The role of the anterolateral ligament in knee’s biomechanics: a case–control retrospective study

Purpose: The aim of this study was to assess the functional and clinical results of patients who underwent ACL reconstruction surgery and were divided into subpopulations related to ACL-associated lesions and focused on ALL-associated lesion. Methods: Our retrospective analysis included 62 patients who underwent standard ACL reconstruction surgery in our hospital from 2014 to 2016. The mean follow-up period was 21 months (range 11–35). We divided the sample into two subpopulations due to the presence or absence of ALL tear at the preoperative MRI. In 42 patients out of 62 (68%), ALL lesion was evident. We evaluated in both subpopulations the ACL failure rate, the functional outcomes rated with IKDC, KOOS, Lysholm scores and the clinical assessment of anteroposterior and rotatory instability with the Lachman test and pivot-shift test. Results: The overall re-injury rate in our cohort of patients was 4.8% with a smaller but not a significant difference between the two groups. A statistically significant difference was observed for the three functional scores, favoring the isolated ACL-lesion group (p < 0.05). Similarly, a better Lachman score was observed in the isolated ACL-lesion group, without statistical significance (p = 0.77); overall, the rate of positive test was lower in the isolated ACL-lesion group. We observed a significant difference of residual rotatory instability (positive pivot-shift test) in the two subpopulations (p = 0.036), and 9% of patients in the ACL + ALL lesion group showed residual jerk or subluxation. Conclusion: The additional ALL reconstruction/repair surgery should always be considered in patients with evident ALL tear at the preoperative MRI