Offset Ratio Research Articles

China's forest carbon sinks and mitigation potential from carbon sequestration trading perspective

To achieve carbon peaking and neutrality goals, China is establishing a national unified carbon emission trading market, especially including forest carbon sequestration market. This study assesses the potential of China’s forest carbon sinks and mitigation potential. We use the Global Forest Products Model to simulate the dynamic changes in China's forest resources from 2018 to 2060, under different carbon sequestration prices scenarios. The projection results indicate that China's forest carbon sinks will be 1.26 Pg (peta-grams) in 2021–2030 and 6.78 Pg in 2021–2060, giving an offset ratio of 4.9–7.0 % and 13.2–18.2 % of China's projected carbon emission in the same period, respectively. Therefore, China's forest carbon sinks will play an important role in carbon peaking and neutrality goals. Meanwhile, forest carbon trading has the potential to increase China's forest carbon sequestration, although the impact may not be immediately apparent. The additional increase in forest carbon sinks from carbon sequestration trading scenarios will not exceed 1.6 % of China’s total carbon emissions between 2021 and 2030. At the current carbon trading price in China ($6.84/t), the increase in forest carbon sinks resulting from forest carbon trading will give an offset ratio of approximately 1 % of total carbon emissions from 2021 to 2060. When the carbon price rises, this offset ratio is 2.3 % to 3.1 % ($25/t), 4.1 % to 5.6 % ($54/t). China should therefore hasten the integration of forest carbon sinks into the national carbon emission unified market and boost the carbon trading price by policy design and market adjustment, or government directly compensate for the forest carbon sequestration function. For forest carbon sinks to play their role in reducing the carbon neutral cost of society, China should raise the amount of forest carbon sink CCERs (Chinese Certified Emission Reductions) used to offset carbon emission allowances in key emission units.

Migration law for random parameters rockfall in steeply dipping coal seams

The migration process of rockfall has certain complexity and randomness in steeply dipping coal seams (SDCS). The three-dimensional random migration of rockfall with random parameters cannot be accurately simulated. Taking the transport process of arbitrarily shaped rockfall formed by roof leakage in steep seam working face as the research object, a method for generating rockfall with the random shape of irregular polyhedrons based on the ellipsoid equation is provided. And based on the geographic information system data, such as the contour line of the bottom floor of the working face, the 3D grid model of the bottom floor is established. The random transport process of rockfall in three-dimensional mining space was simulated using Monte Carlo random simulation technology combined with the energy tracking method (ETM) to compile the program, considering the randomness of collision recovery coefficient and friction coefficient between rockfall and working face floor. The influence of randomness of parameters on the migration velocity, angular velocity and energy of rockfall is analyzed. With the increase of the coefficient of variation of parameters, the influence of the randomness of the parameters on the transport characteristics of rockfall becomes greater. The impact of the collision recovery coefficient on the migration process of rockfall is much more significant than that of the friction coefficient. The offset ratio of rockfall increases with the increase of the variation coefficient. The method presented in this paper can be used to simulate the motion of rockfall more accurately, and a theoretical basis is provided for predicting and protecting rockfall hazards.

Posterior Condylar Offset Ratio and Anterior Femoral Cut between Anterior and Posterior Referencing Systems in Total Knee Arthroplasty

Background: The postoperative posterior condylar offset ratio (PCOR) and the anterior femoral cut (AFC) after total knee arthroplasty in the anterior referencing system (ARS) and posterior referencing system (PRS) are controversial. Objective: To compare PCOR and AFC in both referencing systems. Materials and Methods: The present study was a retrospective study that included 331 patients with 443 knees that underwent primary PSTKA. The patients were divided into two groups according to the referencing system. One hundred four knees were selected for the ARS and 104 knees were selected for the PRS by using the systematic sampling method. Preoperative PCOR, postoperative PCOR, and AFC were measured and compared in each group and between groups. Results: Preoperative PCOR and postoperative PCOR in the ARS and PRS were 0.47 (SD 0.04). Postoperative PCOR in the ARS and PRS were not significantly different (p=0.43). The gaps between the tip of the anterior flange of the femoral component and anterior femoral cortex were 24.04% in the ARS and 28.85% in the PRS, with no statistically significant difference (p=0.43). Anterior femoral notching was not found in either group. Conclusion: Both ARS and PRS could preserve the PCOR and showed no statistically significant difference in the AFC after total knee arthroplasty. Keywords: Posterior condylar offset ratio; Anterior referencing system; Posterior referencing system; Anterior femoral cut; Total knee arthroplasty

Effect of Offset Ratio and Plate Motion on Conjugate Heat Transfer in a Turbulent Offset Jet Flow Over the Heated Plate

Abstract The present investigation focuses on studying the conjugate heat transfer behavior for a turbulent offset jet flow over a heated plate moving uniformly in a positive axial direction. Heat transfer from heated walls to flowing fluids is a subject of great scientific interest and practical importance due to many industrial applications like cooling hot rolling sheets and slabs, cooling continuous casting, etc. The conjugate technique adopted in the present investigation requires consideration of conduction in the solid and the convection from the solid surface to the fluid. For the simulation, a low-Re modified k−ε model developed by Yang and Shih (YS model) is adopted. The YS turbulence model uses the integration-to-wall (ITW) technique which enables it to interpret the variations in fluid and thermal parameters in the near-wall regions without adopting the wall functions. The simulation involves a turbulent offset jet ejecting out of a nozzle at a Reynolds number of 15000, submerged into a stationary environment of Prandtl number 7. The plate at its bottom is heated by constant flux. The various parameters taken into account for observing the thermal behavior are offset ratios (OR=3, 7, and 11), plate velocity ratios (Up=0, 0.5, 1.0, 1.5, and 2), plate thickness ratios (S=0.5, 1.0, and 1.5), and conductivity ratios (K=500, 1000, 1500, and 2000). The temperature distribution diagrams reveal the effect of the parameters mentioned above. The interface temperatures and the Nusselt number suggest better cooling can be achieved at lower offset ratio cases for low-velocity ratios. The contour diagrams and variation of average and local Nusselt numbers suggest the dominating effect of plate motion. A more effective cooling rate is achieved at higher plate velocity, irrespective of the offset ratios.

How Does a Novel In Situ Fixed-bearing Implant Design Perform in Revision Ankle Arthroplasty in the Short Term? A Survival, Clinical, and Radiologic Analysis.

Given the growing number of primary total ankle replacements (TAR), an increase in the number of patients undergoing subsequent revisions might be expected. Achieving a stable and balanced ankle while preserving the remaining bone stock as much as possible is crucial for success in revision TAR. Most reported techniques rely on bulky implants with extended fixation features. Since 2018, we have used a novel, three-component ankle prosthesis for revision that is converted in situ to a fixed-bearing, two-component ankle prosthesis once the components have found their position according to an individual's anatomy. The results of this novel concept (fixation, revision, pain, or function) have not, to our knowledge, been reported. What are the short-term results with this new revision TAR design, in terms of (1) repeat revision surgery, (2) patient-reported outcomes on the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, (3) pain according to the VAS, and (4) radiographic signs of fixation? Between February 2018 and February 2020, we performed 230 TAR surgeries (in 206 patients) for any indication in our clinic. The novel semiconstrained, uncemented Hintermann Series H2 © implant was used in 96% (220 of 230) of procedures (201 patients). Fifty-four percent (119 of 220) of these were converted from an existing TAR to H2, which was the focus of the present study. However, only 45% (54 of 119) of these conversions to H2 were eligible for analysis. These patients had a mean age of 63 ± 12 years, and 43% (23 of 54) were women. The median (range) follow-up time was 3.2 years (2.0 to 4.3). The H2 design allows in situ conversion to a fixed-bearing system, with minimal bone resection. It achieves translational and rotational stability while preserving function and supporting the periarticular soft tissues. We defined repeat revision as exchange of one or both metal components, ankle fusion, or amputation and assessed it using a cumulative incidence survivorship estimator. Factors potentially associated with revision were assessed using Cox regression analyses. Clinical and radiologic outcomes were assessed preoperatively and at the most recent follow-up interval. Clinical outcomes included pain on the VAS (average pain during normal daily activity during the past seven days) and AOFAS score. Radiologic outcomes were the tibial articular surface angle, tibiotalar surface angle, talar tilt angle in the coronal plane, and AP offset ratio in the sagittal plane, as well as radiolucent lines and radiographic signs of loosening, defined as change in position greater than 2° of the flat base of the tibia component in relation to the long axis of the tibia, subsidence of the talar component into the talus greater than 5 mm, or change in position greater than 5° relative to a line drawn from the top of the talonavicular joint to the tuberosity of the calcaneus, as seen on plain weightbearing radiographs. The cumulative incidence of repeat revision after 1 and 2 years was 5.6% (95% CI 0% to 11%) and 7.4% (95% CI 0% to 14%), respectively. With the numbers available, no clinical factors we analyzed were associated with the risk of repeat revision. The median values of all assessed clinical outcomes improved; however, not all patients improved by clinically important margins. The median (range) AOFAS ankle-hindfoot score increased (from 50 [16 to 94] to 78 [19 to 100], difference of medians 28; p < 0.01), and the median pain on the VAS decreased (from 5 [0 to 9] to 2 [0 to 9], difference of medians 3; p < 0.01) from before surgery to follow-up at a minimum of 2 years. Radiographically, lucency was seen in 12% (6 of 49 patients) and loosening was seen in 8% (4 of 49). One of these patients showed symptomatic loosening and was among the four patients overall who underwent revision. We could not assess risk factors for repeat revision because of the low number of events (four). The investigated new in situ fixed-bearing ankle design achieved overall better short-term results than those reported in previous research. Destabilization of the ankle joint complex, soft tissue insufficiency, and possible changes of the joint configuration need an optimal solution in revision arthroplasty. The studied implant might be the answer to this complex issue and help surgeons in the perioperative decision-making process. However, a relatively high percentage of patients did not achieve a clinically important difference. Observational studies are needed to understand long-term implant behavior and possibly to identify ankles benefiting the most from revision. Level IV, therapeutic study.

Aeroacoustic characteristics of supersonic offset jets

The offset jet configuration is one where the jet is discharged at some distance from a solid surface. Although the geometric configuration may look simple, the flow may involve several complexities. In propulsion systems, the high-speed jet generated from the rear engine of an aircraft, flowing nearby the fuselage, can be treated as an offset jet. In this work, an experimental investigation of the interaction noise due to circular high-speed offset jets is performed in an anechoic environment at different nozzle pressure ratios and offset ratios (height of the jet centerline above the plate per nozzle width). A large horizontal plate placed over a height-adjustable stand is used as the offset plate. Acoustic characteristics such as overall sound pressure level and the directivity pattern of free and offset jets are compared for different nozzle pressure ratios. The effect of offset ratio on noise characteristics is also investigated. Flow visualization is also carried out to understand the shock structure and its noise generation mechanism. Acoustic characteristics reveal that noise levels are higher for an offset jet compared to a free jet. Sound pressure levels for offset ratio 0.5 are lower than those for other offset ratios. The noise levels are higher for offset ratio 1.0 due to the presence of feedback tone. Schlieren visualization studies also corroborate the above characteristics.

Maximum utilization of nacre-mimetic composites by architecture manipulation and interface modification towards critical damage state

Diverse ultrahigh-strength platelets offer immense promise for high-efficient energy-absorbing design of nacre-mimetic composites. Yet, incompatible interfacial bonding has greatly restricted the pull-out toughening efficiency to a superior level, resulting in insufficient utilization of platelet strength advantages. Herein, we demonstrate an ingenious critical damage state (CDS) control method to utterly exert the energy absorption potential of nacre-mimetics by pursuing the most efficient toughening mode, which is a universal maximum utilization strategy applicable to platelets with arbitrary strengths. Architecture manipulation results suggest that small aspect ratio platelets can generate superb toughness amplification, and stiffening effect is favored for large-size platelets with dense content and high offset ratio, which is consistent with experimental results. More importantly, by identifying the upper limit of shear strength and the lower limit of plastic deformability, we elucidate the interface modification principle imposed on optimized structure to achieve perfect compatibility. Interestingly, we find the uniform staggered pattern is more recommended for superior energy-absorbing design owing to its pronounced strengthening-toughening effect and looser compatibility restriction compared with the random staggered pattern. Furthermore, the proposed CDS control method should not only be generally feasible for nacre-mimetics, but also shed light on other hard/soft layered composite designs targeting utmost synergistic toughening.

Evolution mechanism and elimination strategy for the directional effect in metal droplets horizontal deposition on vertical substrates

A horizontal working mode opens the preliminary research on the microgravity adaptability of the uniform metal micro-droplets deposition manufacturing (MDDM) technique in terrestrial environments, in which droplets are ejected horizontally and successively deposited on a vertical solid surface. However, it's an elusive target to avoid forming defects and ensure good geometric appearance because of the difference in droplet deposition when the substrate travels upward and downward (named directional effect). To overcome this problem, in this work, we investigated the off-center overlapping of a new-coming droplet on a previously deposited and solidified droplet on vertical substrate by using both experimental methods and numerical simulation. The evolution mechanism of directional effect is revealed. On this basis, an elimination strategy is further proposed. The results show that the directional effect is a natural phenomenon in droplets horizontal successive deposition. There is a constant deviation in the spreading factor and the overlapping ratio of the new-coming droplet between uphill and downhill deposition directions under different offset ratio conditions. The directional effect is mainly caused by the irregular geometric morphology of the pre-solidified droplet and the direct action of gravity field, which can be effectively eliminated by reasonably differentiating the deposition step distance in the uphill and downhill deposition modes. To guide for the selection of deposition step, a parameter mapping of the contour morphology of deposition trace is further established. This work provides meaningful guidance to improve the forming accuracy in micro-droplets transversal deposition manufacturing on vertical solid surfaces.

Comparison of the mean flow and turbulence characteristics of a single offset jet and a dual offset jet

This study compares the mean flow characteristics of a dual offset jet, comprising two 2-dimensional or plane turbulent offset jets, to a single offset jet. An in-house computational model is used to solve the incompressible form of the governing equations which are based on the standard k−ϵ Reynolds Averaged Navier–Stokes turbulence model. The offset ratio, defined as the vertical distance from the solid wall to the jet centreline divided by the nozzle width, of the upper jet is varied from 7 to 13, while the same for the lower jet is equal to 3. The jets’ inlet Reynolds number is 10,000 with a turbulence intensity of 5%. The mean flow results reveal that the presence of the second offset jet greatly influences the flow patterns compared to those of the single offset jet, although at some distance downstream of the inlet, the flow fields of both jet configurations resemble that of a classical wall jet. A single recirculation zone is formed underneath the single offset jet, whereas the flow field of the dual offset jet comprises two recirculation zones, one below the lower jet and the other between the two jets. In the pre-impingement region, the dual offset jet experiences a more rapid decay of the jet half width as compared to the single offset jet; however, the rate of growth of the jet half width for the single offset jet is faster than the dual offset jet. The self-similar solutions confirm that the dual offset jet begins to preserve self-similar characteristics for the mean flow field at a downstream distance greater than that for the single offset jet. For a given offset ratio, the total momentum flux for the single offset jet is found to be greater than that for the dual offset jet. Furthermore, the turbulent Reynolds stresses in the neighbourhood of the merging point are greater for the dual offset jet, but near the reattachment point, they are greater for the single offset jet. No self-similar characteristic of turbulence Reynolds stresses is obtained for both the jets. The turbulent kinetic energy budget reveals the highest value of the production term in the outer shear layer of the lower offset jet for the dual offset jet, which is greater than that for the single offset jet.

Fragility analysis of high-span aqueduct structure under near-fault and far-field ground motions

Previous studies have shown that due to the notable characteristics of near-fault pulse-type (NFP) ground motions, such as large velocity pulse, narrow velocity-sensitive region and long period effect, there are significant differences in the seismic response of building structures caused by NFP ground motions and far-field (FF) ground motions. At present, the effect of NFP ground motions on the damage evolution characteristics of the aqueduct is still lacking. In addition, the current seismic design codes do not provide design recommendations for the dynamic response of aqueduct structures under NFP ground motions. The focus of this manuscript is to quantitatively evaluate the fragility of a high-span aqueduct system under NFP and FF ground motions. For this purpose, 10 as-recorded NFP and FF ground motions are considered, and the aqueduct bearing displacements and pier offset ratios are selected as performance evaluation indices. Then, the copula functions are introduced to establish the fragility curve of the high-span aqueduct system considering the seismic demand correlation of the aqueduct bearing and pier components. The results indicate that under same ground motion intensity conditions, the fragility probability of the aqueduct bearings is significantly larger than that of the trough pier under different performance levels, and should be considered in seismic design. In addition, the fragility probability curve of a single aqueduct component is used to describe the fragility probability of the aqueduct system, which overestimates its seismic performance. The fragility probability of a high-span aqueduct system under NFP ground motions is significantly greater than that under FF ground motions. Therefore, seismic safety assessments and seismic designs for the aqueducts should take into account the influence of NFP ground motions.

Study on neutral axis location of common bolts of flush end-plate connections

The external load eccentricity and the end-plate thickness were employed as the research parameters, and experimental studies on the tensile properties of the bolts with flush end-plate in the beam-column joints was conducted under the action of eccentric pulling force (group A) or pure bending moment (group B). Through the analysis of failure mode, the force distribution of bolts and the offset ratio of the neutral axis, the variations of neutral axis location for common bolts with flush end-plate connections were investigated. Based on the load-displacement curves and the joints tensile performance, the finite element (FE) analysis was used for the two sets of tests. A good agreement exists between the numerical results and the experimental results. The neutral axis of bolts continuously moved continuously to the compression zone as the load increased. Increasing the bolts eccentric distance could significantly increase the bolt axial force increment and accelerate the offset of neutral axial to compression zone. Increasing the thickness of end-plate could reduce the bolt axial force increment and delay the offset of neutral axial to compression zone. The simplified elastic calculation method is more conservative in predicting the stress state of common bolted end-plate connections Under the action of eccentric pulling force or pure bending moment. The modified formulae for the bolt force for flush end-plate connections are presented, and the modified results agree well with the experimental results. Under the premise of ensuring the safety of the structure, the modified formulae provide a more accurate description of the stress state of the common bolted end-plate connections, while requiring less material and reducing the joint cost. It is expected that this study will serve as a reference for the structural design and construction of common bolted end-plate connections.

Short-Term Outcomes of a Two-Component Total Ankle Replacement in Revision Arthroplasty

Category: Ankle Arthritis; Ankle; Hindfoot Introduction/Purpose: Given the growing number of primary total ankle replacements (TAR), an increase in the numbers of failed ankles and consecutive revisions might be expected. Achieving a stable and balanced ankle based on stable components while preserving the remaining bone stock as much as possible, are crucial for success in revision TAR. Most reported techniques rely on bulky implants with extended fixation features. Since 2018, we have used a novel 3-component ankle for revision surgery that is converted in situ to a fixed-bearing 2-component ankle once the components have found their position given by the individual anatomy. The purpose of this study was to determine the short-term results of this novel concept in revision TAR. Methods: This single-center retrospective cohort study included 57 patients (57 ankles, mean age 63+-13 years) treated for failed TAR with the semi-constrained HINTERMANN Series H2© (H2) implant between February 2018 and February 2020. Survival analysis was performed and potential risk factors using Cox regression, were assessed. Clinical and radiological outcomes were assessed preoperatively and at the last follow-up. Clinical outcomes included pain on a visual analog scale (VAS), the American Orthopaedic Foot &amp; Ankle Society (AOFAS) ankle hindfoot score and patient satisfaction. Radiological outcomes were tibial articular surface angle (TAS), tibiotalar surface angle (TTS), talar tilt angle (TT) in the coronal plane and anteroposterior offset (AP-Offset) ratio in the sagittal plane, as well as signs of radiolucency and/or loosening on plane weightbearing radiographs. Results: The median follow-up was 2 (2.0 to 4.0) years. The cumulative incidence for secondary revision after 1 and 2 years was 5.1% (95%CI 0-11) and 7.4% (0-14) respectively. Four patients needed a secondary revision (three for pain/arthrofibrosis and one for aseptic loosening). While the AOFAS hindfoot score increased from median 54 (range 9-94) to 75 (19-98) (p=0.00001), satisfaction increased from moderate to good (p=0.0017). Radiographically, all components were stable without signs of increased shear-forces in terms of loosening or radiolucency. Conclusion: Obtained results with the novel customized semi-constrained total ankle implant design at short-term are encouraging, with a satisfactory survival rate and acceptable revision rate. The fixation concept without extended fixation features was shown to last against increased shear forces.

The Cochlea in Branchio-Oto-Renal Syndrome: An Objective Method for the Diagnosis of Offset Cochlear Turns.

An "unwound" or "offset" cochlea has been described as a characteristic imaging feature in patients with branchio-oto-renal syndrome, and recently recognized to be associated in particular to those with EYA1 gene mutations. Determination of this feature has traditionally relied on subjective visual assessment. Our aim was to establish an objective assessment method for cochlear offset (the cochlear turn alignment ratio) and determine an optimal cutoff turn alignment ratio value that separates individuals with EYA1-branchio-oto-renal syndrome from those with SIX1-branchio-oto-renal syndrome and healthy controls. Temporal bone CT or MR imaging from 40 individuals with branchio-oto-renal syndrome and 40 controls was retrospectively reviewed. Cochlear offset was determined visually by 2 independent blinded readers and then quantitatively via a standardized technique yielding the cochlear turn alignment ratio. The turn alignment ratio values were compared between cochleae qualitatively assessed as "not offset" and "offset." Receiver operating characteristic analysis was used to determine the ability of the turn alignment ratio to differentiate between these populations and an optimal cutoff turn alignment ratio value. Cochlear offset and turn alignment ratio values were analyzed for each branchio-oto-renal syndrome genotype subpopulation and for controls. The turn alignment ratio can accurately differentiate between cochleae with and without an offset (P < .001). The optimal cutoff value separating these populations was 0.476 (sensitivity = 1, specificity = 0.986, J = 0.986). All except 1 cochlea among the EYA1-branchio-oto-renal syndrome subset and all with unknown genotype branchio-oto-renal syndrome had a cochlear offset and a turn alignment ratio of <0.476. All except 1 cochlea among the SIX1-branchio-oto-renal syndrome subset and all controls had no offset and a turn alignment ratio of >0.476. There is a statistically significant difference in turn alignment ratios between offset and nonoffset cochleae, with an optimal cutoff of 0.476. This cutoff value allows excellent separation of EYA1-branchio-oto-renal syndrome from SIX1-branchio-oto-renal syndrome and from individuals without branchio-oto-renal syndrome or sensorineural hearing loss. The turn alignment ratio is a reliable and objective metric that can aid in the imaging evaluation of branchio-oto-renal syndrome.

A radiological index that influences the outcome following patellofemoral joint arthroplasty: the anterior trochlea offset ratio

PurposeAlthough largely successful, patellofemoral joint arthroplasty (PFA) has a less than satisfactory outcome in some patients. It was hypothesized that certain factors can be identified on radiological review that correlate with poor patient reported outcomes following PFA.MethodsA retrospective cohort review of 369 patients undergoing PFA at our institution between 2005 and 2018 identified 43 “poor outcome” patients with an Oxford Knee Score (OKS) of less than 20 at 2 years follow up. These cases were matched by sex and age with 43 “good outcome” patients who had an OKS above 40 at 2 years post-op. Multiple radiological measurements were performed including anterior trochlea offset ratio (ATOR), component flexion/extension, component varus/valgus, component to bone width ratio and retinacular index. The OKS PROM was the primary outcome of the study. Stepwise logistic regression was performed to analyze the differences in radiological indices between the two groups.ResultsIntraclass correlation coefficients for inter-observer and intra-observer reliability were 0.90–0.98 for all indices measured. The only index demonstrating statistical significance between the groups was the ATOR (p = 0.003). The good outcome group had a mean ATOR of 0.19 whereas the poor outcome group had a mean ATOR of 0.24.ConclusionsLower ATOR on radiological review was strongly associated with improved outcomes following PFA. The surgeon should therefore take particular care to prevent increasing the anterior offset of the trochlea component when performing PFA.Level of evidenceRetrospective cohort study, Level III.

Factors Associated With Disease Progression in the Contralateral Hip of Patients With Symptomatic Femoroacetabular Impingement: A Minimum 5-Year Analysis

Background: Femoroacetabular impingement (FAI) is one of the most common causes of hip osteoarthritis, yet the factors controlling disease progression are poorly understood. Purpose: To investigate rates of initial and subsequent symptoms in the contralateral hip of patients with FAI, and identify predictors of disease progression (symptom development and surgical intervention) in the contralateral hip. Study Design: Cohort study; Level of evidence, 2. Methods: This prospective study included a minimum 5-year follow-up of the contralateral hip in 179 patients undergoing FAI surgery. Symptoms (moderate pain) and surgical progression were monitored. Univariate and multivariate analyses compared patient-specific and imaging characteristics of symptomatic patients with those who remained asymptomatic to identify factors associated with disease progression. Results: A total of 150 patients (84% follow-up) were followed for a mean of 7.1 years (range, 5-11 years). Thirty-nine of these patients (26% [39/150]) had contralateral hip symptoms at initial evaluation. Of those without contralateral hip symptoms at initial evaluation, 32% (36/111) had developed contralateral hip symptoms by latest follow-up. Those who developed symptoms during the study period had a lower anteroposterior head-neck offset ratio (0.153 vs 0.165; P = .005), decreased total arc of rotation in 90° of flexion (39.9° vs 51.1°; P = .005), and decreased external rotation in 90° of flexion (28.6° vs 37.1°; P = .003) compared with those who never developed symptoms. Age, sex, body mass index, alpha angle, lateral center-edge angle, internal rotation in flexion, and University of California, Los Angeles (UCLA), activity score were similar between these groups. Those with contralateral symptoms at initial evaluation progressed to contralateral surgery at a rate of 41% (16/39) and those who developed contralateral symptoms during the study period progressed to contralateral surgery at a rate of 28% (10/36). Among those with contalateral hip symptoms (either present initially or developed during study period)), younger age (24.6 vs 34.1 years; P < .001) and baseline UCLA activity score ≥9 (P = .003) were associated with progression to surgery. By Kaplan-Meier analysis, 64%, 54%, and 48% of patients remained free of contralateral hip symptoms at 2, 5, and 10 years. Conclusion: At a mean follow-up of 7.1 years, significant symptoms in the contralateral hip of patients with FAI were present in approximately 50% of patients. FAI disease progression (symptom development and surgical intervention) was associated with decreased hip rotation arc, decreased external rotation, and decreased head-neck offset ratio. In symptomatic patients, younger age and UCLA activity score ≥9 were associated with progression to surgery. These findings represent important factors for patient counseling and risk modeling in FAI.

Numerical study on mean flow characteristics for a combined turbulent wall and offset jets with a parallel co-flow

Combined turbulent wall and offset jets with and without the presence of a parallel co-flow stream are investigated using the k-ω turbulence model. We focus on the effects of co-flow velocity on the locations of various characteristic points formed owing to the interaction of wall and offset jets in the dual jet flow. The inlet Reynolds number is taken as 15,000 and the offset ratio is varied from 5 to 11. At low offset ratios, the co-flow velocity effect remains almost negligible. With the progressive increase in co-flow velocity, the characteristic points are gradually relocated towards the further downstream direction with a transverse movement away from the bottom wall whose effect is weakened with the increase in co-flow velocity. Furthermore, regression analysis shows power law and linear correlations of the longitudinal and transverse coordinates of characteristic points with the co-flow velocity and the offset ratio.

A Meta-analysis on the Effectiveness of Offsetting Strategies to Address Harm to Freshwater Fishes.

Offsetting aims to compensate for negative impacts due to authorized anthropogenic impacts associated with development. While anchored into legislation, residual or chronic impacts can occur after offset establishment. Advice and best practice on how to approach these impacts is rare. To address this, we reviewed 30 projects based on a systematic review and meta-analysis in freshwater ecosystems dealing with residual or long-term negative impacts to provide application advice for: habitat creation, habitat restoration, and biological and chemical manipulation. Project information was obtained through Boolean search terms and web-scraping. Habitat creation projects had a pooled effect size of 0.8 and offsetting ratios of 1:5 with high biomass increases of &gt;140% compared to pre-establishment, associated with them. Habitat restoration projects targeted a wide range of species and communities with a pooled effect size of 0.66, offset ratios ranging from 1:1.2 to 1:4.6, and biomass increases generally &gt; 100% compared to pre-restoration. Biological manipulation had the lowest effect size (0.51) with stocking being highly variable both in terms of biomass benefits and project outcomes pointing towards being mostly applicable in cases of direct fish harm not related to habitat aspects. We conclude that (1) all three assessed approaches have a potential application use for offsetting residual or chronic harm with approach-specific caveats. (2) Implementation costs differ across offset methods, with connectivity and side-channel projects having the lowest biomass gain per area costs (3) Time to first benefits required one to two years with time lags needing to be accounted for in the implementation and monitoring process.

The rebounding-coalescing behaviors in drop-on-drop impact on a superhydrophobic surface

The great anti-accumulation performance of drop-on-drop impact on a superhydrophobic surface is beneficial to self-cleaning and anti-icing. Hence, the rebounding-coalescing behaviors in drop-on-drop impingement with varying Weber number and offset ratio are studied experimentally in the present work. The complete regime map of rebounding states is proposed, which can be divided into no-coalesce, jug-like, pancake-like, and pendulum-like rebounding-coalescing behaviors. Subsequently, the increase in the contact time in pendulum-like rebounding-coalescing behaviors is captured and described by a linear model well. Finally, a theoretical prediction based on momentum conservation for the averaged maximal spreading radius of the coalesced droplet is provided. Our approach provides insight into a mechanism of the rebounding-coalescing behaviors, which is helpful for the improvement in related applications.

CFD Investigation of Thermal Characteristics for a Dual Jet with a Parallel Co-flow.

A combined turbulent wall jet and offset jet (also known as the dual jet) with and without the presence of a parallel co-flow stream is studied. The standard k–ω turbulence model is used to predict the turbulent flow. The study focuses on the effects of the co-flow velocity (CFV) on the heat-transfer characteristics of the dual jet flow with the bottom wall maintained at a constant wall temperature. The CFV is varied up to 40% of the jet inlet velocity, and the height of the offset jet is varied from 5 to 11 times the jet width with the inlet Reynolds number taken as 15,000. The heat-transfer results reveal that the local Nusselt number (Nux) along the bottom wall exhibits a peak at the immediate downstream of the nozzle exit, followed by a continuous decay in the rest of the converging region before showing a small rise for a short streamwise distance in the merging region. Further downstream, in the combined region, Nux gradually decreases with the downstream distance. Except the merging region, no influence of co-flow is observed in the other two flow zones (converging and combined regions). In the merging region, for a given offset ratio (OR), Nux remains nearly constant for a certain axial distance, and it decreases as the CFV increases. As a result of the increase in the CFV, the average Nusselt number decreases, indicating a reduction in overall convective heat transfer for higher values of the CFV. A regression analysis among the average Nusselt number (), CFV, and OR results in a correlation function in the form of within the range OR = 5–11 and CFV = 0–40%.

Effect of Parameters of Pool Geometry on Flow Structure in Nature-like Fishway.

Many uncertainties such as variable irregular structure and complex flow conditions bring difficulties to the design of a nature-like fishway. This study defines the main factors and parameters affecting flow conditions such as permeability ratio, offset ratio, bottom slope and pool length to simplify and generalize the irregular geometry of the nature-like fishway. According to the engineering requirements of the Mopiling nature-like fishway, the effect of the above parameters of pool geometry on the flow structure is investigated through a 3D turbulent numerical simulation, and the parameter thresholds are summarized according to the optimization of the flow conditions. The results show that under the same conditions, the maximum velocity of the control section increases with the increase in permeability ratio, bottom slope and pool length, and the offset ratio has limited effect on the maximum velocity of the control section. It is recommended that when the bottom slope is 1/250 and the pool length is 10 m, the permeability ratio should not be greater than 0.30 and the offset ratio should be located between 0.15 and 0.60. When the bottom slope is adjusted to 1/200, it is recommended to control the permeability ratio below 0.20, the offset ratio between 0.30 and 0.60, and the pool length can be adjusted to 8 m. Within the above threshold range of the design parameters, the maximum velocity in the fishway can be basically controlled at about 1.0 m/s. The mainstream in the pool is clear and the flow pattern is good, which can basically satisfy the requirements of fish passing. The relevant design parameters and optimization strategies can provide reference for similar projects.