Span Position Research Articles

The influence of shear surface quality on the mechanical properties of long-span prestressed continuous rigid-frame bridge

PurposeThe long-span continuous rigid-frame bridges are commonly constructed by the section-by-section symmetrical balance suspension casting method. The deflection of these bridges is increasing over time. Wet joints are a typical construction feature of continuous rigid-frame bridges and will affect their integrity. To investigate the sensitivity of shear surface quality on the mechanical properties of long-span prestressed continuous rigid-frame bridges, a large serviced bridge is selected for analysis.Design/methodology/approachIts shear surface is examined and classified using the damage measuring method, and four levels are determined statistically based on the core sample integrity, cracking length and cracking depth. Based on the shear-friction theory of the shear surface, a 3D solid element-based finite element model of the selected bridge is established, taking into account factors such as damage location, damage number and damage of the shear surface. The simulated results on the stress distribution of the local segment, the shear surface opening and the beam deflection are extracted and analyzed.FindingsThe findings indicate that the main factors affecting the ultimate shear stress and shear strength of the shear surface are size, shear reinforcements, normal stress and friction performance of the shear surface. The connection strength of a single or a few shear surfaces decreases but with little effect on the local stress. Cracking and opening mainly occur at the 1/4 span. Compared with the rigid “Tie” connection, the mid-span deflection of the main span increases by 25.03% and the relative deflection of the section near the shear surface increases by 99.89%. However, when there are penetrating cracks and openings in the shear surface at the 1/2 span, compared with the 1/4 span position, the mid-span deflection of the main span and the relative deflection of the cross-section increase by 4.50%. The deflection of the main span increases with the failure of the shear surface.Originality/valueThese conclusions can guide the analysis of deflection development in long-span prestressed continuous rigid-frame bridges.

Three-Dimensional Trajectory and Impingement Simulation of Ice Crystals Considering State Changes on the Rotor Blade of an Axial Fan

Ice crystal icing occurs in jet engine compressors, which can severely degrade jet engine performance. In this study, we developed an ice crystal trajectory simulation, considering the state changes of ice crystals with a forced convection model, indicating a significant difference in impinging ice crystal content on the blade for tiny ice crystals. Then, ice crystal trajectory simulations were performed for the rotor blade of an axial fan to investigate the effects of ice crystal size and relative humidity on collision characteristics. The results indicate that the surrounding air affects the composition of tiny ice crystals before collision, and the flight time until impingement on the rotor blade varies significantly depending on the span position. Among them, ice crystals with a diameter of 50 μm impinge with water content that is most likely to adhere to the blade. Three-dimensional simulation results show that many ice crystals impinge not only on the leading edge, where icing occurs as revealed by the two-dimensional simulations but also on the trailing edge of the hub side. This study emphasizes the importance of evaluating the three-dimensional impingement position and water content in the prediction of ice crystal icing.

Study on the Mechanical Properties of MiC Formworks with Different Material Components

Modular integrated construction (MiC) is a new type of assembled building structure system that consists of prefabricated concrete modules connected using post-cast concrete. To reduce material consumption and realize casting without supporting molds, thin and lightweight concrete formworks (MiC formworks) with a thickness of 30 mm are installed as part of the shear wall. Due to the thinness, concrete pouring tends to cause MiC formwork cracking, mold rising, and other problems. Its stress performance and damage mechanism are not clear. For this reason, three groups of MiC formworks with different material composition types are designed. The static load test is carried out in a graded partition loading mode, and parametric analysis is combined with numerical simulation to systematically study the influence of different material components on the mechanical properties of MiC formworks. The results show that the front cracks of the MiC formworks are mainly distributed under the truss tendons, and the back cracks are mainly distributed in the span position of the adjacent truss tendons. These cracks both occur along the span direction of the MiC formworks. Increasing the concrete strength has a significant effect on improving the load-bearing capacity of MiC formworks, while incorporating steel fibers can significantly improve its deformation and crack resistance. Parametric analysis showed that the steel fiber admixture exhibited limited improvements in the cracking resistance of the panels as the concrete matrix grade increased. The research results provide a practical basis for optimizing the production process of MiC formworks.

Experimental investigation and numerical analysis on the stability of curved CFRP thin-walled pipe truss

This paper investigates the stability performance of a large-scale carbon fiber reinforced composite (CFRP) truss used in the keel structure of a stratospheric airship. An ultimate load-bearing test was performed on an approximately 4 m long curved CFRP thin-walled pipe truss, which was reduced to sliding supports at both ends to simulate force conditions in the normal service phase. A modified initial geometric imperfection (GI) simulation method was employed to conduct a linear and nonlinear finite element (FE) buckling analysis of the structure, considering the composite lay-up of the thin-walled pipe. Parametric analysis studies were also conducted to improve simulation accuracy and lightweight design. Results show that the structure exhibits linear behavior under the ultimate load level, with failure occurring at the span position of the lower chord. The FE model predicts the ultimate load capacity and stiffness of the structure accurately, and the parametric analysis reveals the significance of choosing a reasonable imperfection form and amplitude for the FE analysis, as well as the significant effect of ply orientation on structural performance. This study provides valuable insights into the design and optimization of CFRP trusses used in the keel structure of stratospheric airships.

Damage Detection Method of Simply Supported Beams Based on Difference of Nearby Difference Curvature Index

In order to improve the effectiveness and convenience of damage identification of two-span continuous beams, a new damage identification index <I>D</I>_i based on the deflection data of beam under concentrated load, which takes local flexural stiffness and shear stiffness as damage identification parameter, was proposed. The damage detection method based on <I>D</I>_i includes four main steps: arranging vertical deflection measurement points at equal intervals on the beam body and applying a concentrated load <I>F</I> at the mid span position of one of the spans. After measuring the <i>y</i>_i value at each measurement point, the differential deflection curvature value 1/<i>ρ</i>_ican be calculated; After obtaining specific values of <I>D</I>_iaccording to the definition, a graph with <I>D</I>_i as the vertical coordinate and the positions of each measuring point on the longitudinal axis of the beam as the horizontal coordinate can be drawn; The mutation position on the graph can indicate the location of the damage: if the mutation starts from point <i>j</i>, it indicates that the damage occurs in the area between measurement points <i>j</i>+1 and <i>j</i>+2; By selecting any two values from <I>D</I>_i-1, <I>D</I>_i, and <I>D</I>_i+1 and solving the corresponding definition equation simultaneously, the degree of beam damage characterized by the relative change in local stiffness can be determined. The results of numerical example validation indicate that this method has good damage identification performance.

A Span-based Multi-Modal Attention Network for joint entity-relation extraction

Joint extraction of entities and their relations not only depends on entity semantics but also highly correlates with contextual information and entity types. Therefore, an effective joint modelling method designed for handling information from different modalities can lead to a superior performance of the joint entity and relation extraction. Previous span-based models tended to focus on the internal semantics of a span but failed to effectively capture the interactions between the span and other modal information (such as tokens or labels). In this study, a Span-based Multi-Modal Attention Network (SMAN) is proposed for joint entity and relation extraction. The network introduces a cloze mechanism to simultaneously extract the context and span position information, and jointly models the span and label in the relation extraction stage. To determine the fine-grained associations between different modalities, a Modal-Enhanced Attention (MEA) module with two modes is designed and adopted in the modelling process. Experimental results reveal that the proposed model consistently outperforms the state-of-the-art for both entity recognition and relation extraction on the SciERC and ADE datasets, and beats other competing approaches by more than 1.42% F1 score for relation extraction on the CoNLL04 dataset. Extensive additional experiments further verify the effectiveness of the proposed model.

Sensitivity Analysis of Influencing Factors of Underground Civil Air Defense Construction Vibration under Vehicle Load

Grey correlation theory is an uncertainty analysis method, which can find the relevance of various factors studied through certain data processing in incomplete information and find the main influencing factors. In order to study the influence of vehicle load on the vibration of underground civil air defense construction, taking the civil air defense construction at the intersection of Zhongzhou Middle Road and Shachang South Road in Luoyang as the study subject, based on the field measured data, and using ANSYS to expand the working conditions, this paper studies the influence of such factors as elastic modulus of concrete, thickness of overburden layer, density of soil layer, elastic modulus of soil layer, vehicle speed, and vehicle mass on the vibration of the civil air defense construction through the grey correlation sensitivity analysis method. The field measurement and numerical simulation results show that the displacement, velocity, and acceleration values decrease gradually from the mid−span position of the roof to the wall. Displacement, velocity, and acceleration are important indexes for evaluating vibration. The grey correlation degree of the influencing factors of displacement and velocity from large to small is density of soil layer, vehicle mass, vehicle speed, elastic modulus of concrete, elastic modulus of soil layer, and thickness of overburden layer. The grey correlation degree of the influencing factors of acceleration from large to small is vehicle mass, layer of density of soil layer, vehicle speed, elastic modulus of concrete, elastic modulus of soil layer, and thickness of overburden layer. The grey correlation degree of soil layer density, vehicle mass and vehicle speed to displacement, velocity, and acceleration is 0.7951–0.9993, which indicates that their influence is significant. This study can provide reference for the design and construction of similar civil air defense constructions.

Low-velocity impact behavior of SWRH82B steel wires considering different section shapes based on experiments and simulations

SWRH82B steel wires are commonly used in suspended-cable structures, large-span structures, and cable-stayed bridges owing to their light weight, strong bearing capacity, and safe and reliable operation. In this study, the dynamic mechanical performance of SWRH82B steel wires under low-velocity impact was studied experimentally and numerically. A drop-hammer impact test system was adopted for the impact experiments, considering the influence of the specimen diameter, specimen span, indenter shape, and impact position. Two-section steel wires, including circular and Z-shaped wires, were investigated. The experimental results indicated that local denting deformation occurred at the impact position with a lower impact energy, and wire breakage occurred near the position of the clamping device with a larger impact energy. Circular wires were stronger and stiffer than Z-shaped wires of the same diameter because they can provide a higher impact resistance and stronger energy absorption capacity with a regular section shape. The experimental data indicated that the specimen diameter positively affects the impact bearing capacity, providing more flexural rigidity. However, the specimen span negatively influences the dynamic performance of both types of steel wires; a greater increase in peak load was observed when using a cylinder hammer. In addition, a finite element model was established to further analyze the failure modes and discuss a larger range of parameters. Finally, a numerical model of prestressed steel wires was developed using ABAQUS/EXPLICIT, with the results indicating that the prestress force could strengthen the impact resistance of steel wires at a lower level.

Interannual temperature variability is a principal driver of low-frequency fluctuations in marine fish populations

Marine fish populations commonly exhibit low-frequency fluctuations in biomass that can cause catch volatility and thus endanger the food and economic security of dependent coastal societies. Such variability has been linked to fishing intensity, demographic processes and environmental variability, but our understanding of the underlying drivers remains poor for most fish stocks. Our study departs from previous findings showing that sea surface temperature (SST) is a significant driver of fish somatic growth variability and that life-history characteristics mediate population-level responses to environmental variability. We use autoregressive models to simulate how fish populations integrate SST variability over multiple years depending on fish life span and trophic position. We find that simulated SST-driven population dynamics can explain a significant portion of observed low-frequency variability in independent observations of fisheries landings around the globe. Predictive skill, however, decreases with increasing fishing pressure, likely due to demographic truncation. Using our modelling approach, we also show that increases in the mean and variance of SST could amplify biomass volatility and lessen its predictability in the future. Overall, biological integration of high-frequency SST variability represents a null hypothesis with which to explore the drivers of low-frequency population change across upper-trophic marine species.

Elimination of moving vehicles effects on modal identification of beam type bridges

The modal parameters identified under operation conditions are normally employed for bridge damage detection. However, the moving vehicles are usually deemed as part of the operation conditions without considering their mass property. Thus, the identified modal parameters belong to the vehicle-bridge system rather than the bridge itself, which would affect the effectiveness of subsequent damage detection. In this paper, the effects of moving vehicles on the identified frequencies and mode shapes under operation conditions are investigated via finite element model. The necessary of considering the moving vehicle effects is demonstrated by comparing the modal parameters variations induced by the moving vehicle and bridge damage. Then the empirical formulas to eliminate the moving vehicle effects considering the vehicle mass, velocity, bridge span and relative position are established by using the orthogonal test and least square method. Finally, examples are conducted to verify of the effectiveness of the proposed empirical formulas.

Fatigue Damage Monitoring of Wind Turbine Blades by Using the Kalman Filter

Fatigue damage accumulation needs to be monitored for extending the lifetime of horizontal axis wind turbines. To monitor accumulation of fatigue damage, this paper proposes a blade load and fatigue damage monitoring system consisting of physics models coupled with the Kalman filter (KF). The proposed monitoring system estimates bending moment distribution along the blade as a time series from 1 Hz data collected by a supervisory control and data acquisition (SCADA) system and from 20 Hz strain sensor data collected at the blade root. Static load is computed on the basis of blade element and momentum theory from SCADA data, whereas dynamic response of the blade is computed by assuming a mass–spring–damper system. The KF corrects the estimated moment distribution with moment measured at the blade root. The monitoring system is demonstrated and validated by installing it on a 2 MW floating downwind turbine and estimating strain and fatigue damage at the medium span position of the blades, where a strain sensor is installed. The validation results show that strain wave forms and fatigue damage estimated by the monitoring system with the KF are consistent with those computed from the strain measurement with sufficient accuracy for structural health monitoring.

Hover flight control of X-shaped flapping wing aircraft considering wing–tail interactions

The dynamic modelling and attitude controller design of a flapping wing aircraft, Beihawk, were investigated in this study. The aircraft features of an X-shaped flapping wing configuration, tail control surfaces installed downstream of the main flapping wings for roll and pitch control, and a tail rotor for yaw control. Unsteady effects including partial leading edge suction, induced flow, and post-stall behaviour, were considered in the aerodynamic modelling. Flapping-wing-induced flow was found to be crucial to the tail control force generation for the utilized aircraft layout. A periodically time-varying wing–tail interaction model was thus established, based on which a double-loop controller was designed to enable stable hovering of the aircraft. The stability of the nonlinear hovering-based manoeuvre was studied by manifold theory, based on the proposed wing–tail interaction model. Simulations and flight experiments on Beihawk were conducted to verify the proposed theory. It was found that the controller considering wing–tail interaction effect enabled more stable hover flight compared with traditional PD controller. In addition, it was found a wider stability region can be obtained by a higher flapping-wing-induced flow velocity. The functions between this velocity and the influencing factors, such as thrust force, wing span and tail installation position, are also presented. Besides, a visual parameter stability boundary between the vertical and pitching velocity is given. Relevant conclusions are vital in active flight envelope protection.

Unsteady Steam Turbine Optimization Using High-Fidelity Computational Fluid Dynamics

Abstract This paper presents the computational methodology and experimental investigations accomplished to enhance the efficiency of a turbine stage by applying non-axisymmetric profiling on the rotor hub wall. The experimental setup was a two-stage axial turbine, which was tested at “LISA” test facility at ETH Zurich. The first stage was considered to create the flow history for the second stage, which was the target of the optimization. The hub cavity of the second stage was designed with large dimensions as a requirement of a steam turbine. The goal was to optimize the interaction of the cavity leakage flow with the rotor passage flow to reduce the losses and increase efficiency. The computational optimization was completed using a genetic algorithm coupled with an artificial neural network on the second stage of the test turbine. Unsteady time-accurate simulations were performed using in-house developed “MULTI3” solver. Besides implementing all geometrical details (such as hub and tip cavities and fully 3D blade geometries) from the experimental setup into the computational model, it was learned that the unsteady upstream effect could not be neglected. A novel approach was introduced using unsteady inlet boundary conditions to consider the multistage effect while reducing the computational cost to half. The importance of this implementation was tested by performing a steady simulation on the optimized geometry. The predicted efficiency gain from steady simulations was 4.5 times smaller (and negligible) compared to the unsteady approach. Excluding the cavity geometry was also assessed in a different simulation setup showing 3.9% over-prediction in the absolute efficiency value. Comprehensive steady and unsteady measurements were performed utilizing pneumatic, fast response aerodynamic probe (FRAP), and fast response entropy probe (FENT) on the baseline and profiled test cases. The end wall profiling was found to be successful in weakening the strength of the hub passage vortex by a 19% reduction in the under-over turning. As a result, the blockage was reduced near the hub region leading to more uniform mass flow distribution along the span. The flow angle deviations at the higher span position were also corrected due to better control of the flow angles. Furthermore, the improvements were confirmed by reductions in entropy, secondary kinetic energy, and pressure unsteadiness. The accurate computational implementations led to an excellent agreement between the predicted and measured efficiency gain.

The Fouling Behavior of Steam Generator Tube at Different Positions in the High-Temperature Water

The fouling behavior of a steam generator (SG) tube was investigated at different positions after 500 h of immersion in high-temperature water. A triple-layer structure of fouling appeared at both the crevice position and the free span position, namely, the large, dispersedly distributed deposition layer on the top; the small and faceted outer layer; and the relatively continuous inner layer. There was no obvious positional effect on the thickness of the inner layer. However, in the crevice position, the density of the deposited particle and the thickness of the outer layer was much higher than those of the free span position. The tube support plate (TSP) made of 410 stainless steel contributed significantly to the fouling behavior of the SG tube in the crevice between the SG tube and the TSP.

Aerodynamics and Propulsive Efficiency of a Blended-Wing-Body Aircraft with Distributed Propulsion System During Takeoff

A blended-wing-body aircraft with distributed propulsion system is a new design concept proposed in recent years to achieve the N + 3 goal. Distributed engines can be embedded on different positions on the upper surface of the aircraft due to its smaller size compared with the traditional engines. Different installation positions can influence not only the aerodynamic characteristics but also the engine performance, especially during the off-design conditions such as takeoff condition. Thus, a propulsion/airframe integration analysis method was developed to calculate the performance of several configurations with different engine positions at takeoff condition. We found that there is strong coupling between the aerodynamics and propulsion efficiency, and that the span position of the propulsion system has more significant effects on the performance of the aircraft compared with its chord position.

Experimental study of flow through compressor Cascade

The objective of this research work is to study the behaviour of flow at the inlet, within the blade passage and at the exit of a compressor cascade. For this purpose, a cascade with six numbers of aerofoil blades was designed and constructed. The cascade was fitted on the cascade test tunnel. Out of six blades two were instrumented for measuring the pressure distribution on the pressure and suction surface. The blades had a parabolic camber line, with a maximum camber position at 40% of the chord from the leading edge of the blade. The profile of the blade was C4, height of the blade was 160mm, chord length was 80mm, camber angle was 45° and stagger angle was 30°. Similarly, the length of the cascade was 300mm, span was 160mm, pitch was 60mm, the actual chord of the cascade was 80mm, the axial chord of the cascade was 70mm, the stagger angle of the cascade was 30° and the pitch-chord ratio was 0.75. The data was taken and analyzed at −500% of the axial chord before the cascade, −25% of the axial chord before the leading edge, 25%, 50%, 75% and 150% of the axial chord from the leading edge of the blade. The readings were taken from the cascade wall to the mid span position along the pitch wise direction. The angle of incidence was also changed during the experiment and varied from i=−50°, −30°, −10° to 5°.

Wind Shear, Gust, and Yaw-Induced Dynamic Stall on Wind-Turbine Blades

This study examined the effect of a spanwise angle of attack gradient on the growth and stability of a dynamic stall vortex on a rotating blade. It was found that a spanwise angle of attack gradient induces a corresponding spanwise vorticity gradient, which, in combination with spanwise flow, results in a redistribution of circulation along the blade. Specifically, when replicating the angle of attack gradient experienced by a wind turbine at the 30% span position during a gust event, the spanwise vorticity gradient was aligned such that circulation was transported from areas of high circulation to areas of low circulation. This in turn increased the local dynamic stall vortex growth rate, which corresponds to an increase in the lift coefficient, and a decrease in the local vortex stability at this point. Reversing the relative alignment of the spanwise vorticity gradient and spanwise flow results in circulation transport from towards areas of high circulation generation, which acted to reduce local circulation and thereby stabilize the vortex. This circulation redistribution behaviour describes a mechanism by which the fluctuating loads on a wind turbine are magnified, which is detrimental to turbine lifetime and performance.

Atlantic Bottlenose Dolphins (Tursiops truncatus) as A Sentinel for Exposure to Mercury in Humans: Closing the Loop.

Mercury (Hg) is a ubiquitous global contaminant with important public health implications. Mercury is released from a variety of anthropogenic, industrial processes, enters the earth's atmosphere and is re-deposited onto the earth’s surface in rainfall. Much of this Hg enters the oceans which cover the majority of the earth’s surface. In the marine environment, inorganic Hg is converted to the most toxic form of the element, methylmercury, and biomagnified through the trophic levels of the food web. The bottlenose dolphin (Tursiops truncatus) is the apex predator in many estuarine and coastal ecosystems. Due to their long life span and trophic position, bottlenose dolphins bioaccumulate high concentrations of contaminants including Hg, thus making them an important sentinel species for ecosystem and public health. Bottlenose dolphins in Florida bioaccumulate high concentrations of Hg in their blood, skin and internal organs. The concentrations of Hg in blood and skin of bottlenose dolphins of the Indian River Lagoon, FL (IRL) are among the highest reported world-wide. In previous studies, we demonstrated associations between concentrations of total Hg in the blood and skin of IRL dolphins and markers of endocrine, renal, hepatic, hematologic and immune system dysfunction. The predominant manifestation of exposure to mercury in humans is neurotoxicity. During the 1950s and 1960s, residents of Minamata bay, Japan were exposed to high concentrations of methyl mercury as the result of ingestion of fish and shellfish that had become contaminated in this infamous environmental disaster. Affected adults had severe motor and sensory abnormalities often leading to death. Methyl mercury crosses the placenta during pregnancy. Children exposed in utero were born with multiple congenital anomalies and also suffered from neurologic disorders. Significantly, local cats that consumed Hg contaminated fish developed severe signs of neurotoxicity which led to their subsequent description as the “dancing cats of Minamata bay”. Unfortunately, the cause of these strange manifestations in cats was not recognized in time to prevent hundreds of additional cases from occurring. More recent studies have shown that exposure to mercury as a result of seafood consumption during pregnancy may result in multiple cognitive and neurodevelopmental effects in children. The levels of mercury found in bottlenose dolphins and the health effects we identified alerted us to the possibility of an important public health hazard. The IRL occupies 40 percent of the east coast of Florida and is bordered by counties with approximately 2.5 million human inhabitants. Therefore, we hypothesized that local inhabitants in communities bordering the IRL could be at risk of exposure to Hg from the consumption of fish and shellfish. We measured hair Hg in 135 local residents and found a mean concentration of 1.53 µg/g which was higher than that from previous studies of sport fishermen and coastal residents in other states. Over 50% of participants had a hair Hg concentration which exceeded the U.S. EPA exposure guideline. Hair Hg concentration was directly related to the frequency of seafood consumption and to the proportion of fish and shellfish obtained from local recreational sources. This study clearly exemplifies the importance of an animal sentinel in identifying a public health hazard and is virtually unique in “closing the loop” between animal and human health.

Broadening an understanding of problem gambling: The lifestyle consumption community of sports betting

This paper presents a study offering insight and understanding of the emerging concept of lifestyle consumption community in the context of sports betting in Australia. Recent research has identified the utility of socio-cultural approaches for understanding gambling, broadening the scope of research beyond an individual psychology perspective. Heretofore, the concept of ‘problem gambling’ has mostly focused on pathological gamblers. However, scholars in the field have argued for a repositioning of the framing of gambling. This study utilizes an interpretivist research approach, featuring friendship group interviews with young adult non-pathological gamblers engaging in sports betting aged 18–30. The findings offer insights on the locus, power structure, purpose, marketing potential, time span, structure, and social position of lifestyle consumption communities. The utility of consumer culture theory research for offering a broader understanding of gambling is identified. Implications for marketing management, consumer culture theory, and ideas for future research are discussed.

Digit Span in Dyslexia: Variations According to Language Comprehension and Mathematics Skills

The aim of this study was to investigate digit span performance in dyslexia. It was hypothesised that differences would be found in accordance with subgrouping by language comprehension and mathematic skills, and by analyses of how the digit span scores were attained. Two digit span tasks were given to a group of dyslexic children and controls (n = 57), mean age 12.62 (SD = 1.43). The tasks were “Digit Span” of the WISC-R, and “Digit Span 2,” where the use of back-up strategies like finger counting and lip reading were restricted. As expected, the digit span scores were significantly lower in the dyslexia group than in the control group. Restrictions of back-up strategies did not alter the scores in the control group, while the scores were lowered in the dyslexia group. Further analyses of longest digit span, serial recall, and serial position indicated different retrieval patterns in the subgroups. The subgroup with good language comprehension and mathematic skills (n = 12), showed impaired serial recall especially in backward recall. The subgroup with good language comprehension skills, but with mathematics impairment (n = 9), showed impaired serial recall in both forward and backward recall. The subgroup with language impairments (n = 16), recalled fewer digits than the two other subgroups. The findings were discussed in relation to the “Phonological loop” of the Multi Component Model ofWorking Memory, and implications for intervention were discussed.