Intermittent Contact Research Articles

Fuel Particle Heat Transfer Part 2: Radiation and Convection during Spreading Laboratory Fires

ABSTRACT The effects of radiation and convection in determining the heating that leads to ignition of fuel particles were explored using experiments with spreading laboratory fires and a numerical fuel particle heating model. As a follow-on to “Fuel Particle Heat Transfer, Part 1” (this issue), two sizes of square wood fuel particles (1 mm and 12 mm) were instrumented with fine-wire thermocouples to measure particle surface temperatures and adjacent gas temperatures. Radiation heat flux from the approaching fire was measured at the fuel bed particle location. Seven laboratory fires with varying fuel beds, spread rates, and wind speeds were used to measure the conditions experienced by both particles. Experimental results demonstrated that intermittent flame contact ahead of the advancing flame front was principally responsible for heating fuel particles to ignition even with peak irradiance up to 44 kW/m2. A two-dimensional numerical fuel particle heat transfer model was employed to separate the influences of the measured irradiance (radiation) and gas temperature (convection) on particle heating as the flame front approached. Results demonstrated that radiation heating was insufficient for ignition of both particle sizes during the spreading laboratory fires. The low convective heat transfer of the 12 mm particle did not significantly cool the particle, and the brief duration of irradiance was insufficient for ignition. The greater 1 mm particle convective heat transfer offset radiant heating by convectively cooling with ambient air, but rapidly heated the particle during intermittent impingement of hot gases from the flaming front leading to particle pre-ignition.

Graphene-mediated suppression of Leidenfrost effect for droplets on an inclined surface

The ability to delay the Leidenfrost effect is desirable in many engineering applications operating at a temperature above the Leidenfrost point. Unlike previous studies that frequently demonstrate the suppression of the Leidenfrost effect via a free-falling droplet on the horizontally-aligned heated-surfaces, here, we investigate the suppression of the Leidenfrost effect for a droplet that rolls on an inclined heated-surface coated with graphene for cooling enhancement. With graphene-coated surfaces, we observe the suppression of the Leidenfrost effect at a temperature up to 290 °C, representing more than 100 °C increase of Leidenfrost point as compared to that on an uncoated surface. This can be attributed to the unique rapid water permeation characteristics of graphene that enables vapor to escape through the nanostructure, obstructing the formation of a continuous vapor layer. Specifically, when a droplet rolls onto the graphene-coated surface, we observe three interesting regimes: Regime-I (contact boiling), Regime-II (intermittent contact boiling), and Regime-III (transient contact boiling). In Regime-I, the droplet in full contact and pinned on the graphene-coated surface, leading to a largest reduction in surface temperature. In Regime-II, the droplet in partial contact with the graphene-coated surface and subsequently bounced in the reversed direction. Finally, in Regime-III, the droplet momentarily in contact with the graphene-coated surface and quickly bounced in the forward direction. Overall, with the graphene-coated surface, we observe an up to 64 °C reduction in the temperature of the heated surface.

Mediating Between Contact Feasibility and Robustness of Trajectory Optimization Through Chance Complementarity Constraints.

As robots move from the laboratory into the real world, motion planning will need to account for model uncertainty and risk. For robot motions involving intermittent contact, planning for uncertainty in contact is especially important, as failure to successfully make and maintain contact can be catastrophic. Here, we model uncertainty in terrain geometry and friction characteristics, and combine a risk-sensitive objective with chance constraints to provide a trade-off between robustness to uncertainty and constraint satisfaction with an arbitrarily high feasibility guarantee. We evaluate our approach in two simple examples: a push-block system for benchmarking and a single-legged hopper. We demonstrate that chance constraints alone produce trajectories similar to those produced using strict complementarity constraints; however, when equipped with a robust objective, we show the chance constraints can mediate a trade-off between robustness to uncertainty and strict constraint satisfaction. Thus, our study may represent an important step towards reasoning about contact uncertainty in motion planning.

АНАЛИТИЧЕСКОЕ ИССЛЕДОВАНИЕ СИЛ ШЛИФОВАНИЯ ПРИ НАЛОЖЕНИИ УЛЬТРАЗВУКОВЫХ КОЛЕБАНИЙ С ВЫСОКОЙ АМПЛИТУДОЙ

An analytical study of the grinding forces under the superposition of ultrasonic vibrations (UV) with an amplitude providing intermittent contact of the abrasive grains of the circle with the workpiece, was performed. The grinding force was defined as the sum of the forces from the individual grains of the circle located on different sections of their trajectory relative to the treated surface of the workpiece. When the grain is moved in the contact zone of the circle with the workpiece, its operating mode changes and depends on the phase of vibrations. Moving relative to the workpiece, the grain performs plastic deformation and micro-cutting, on part of the trajectory it can come out of contact with the workpiece. The sequence of implementation of these modes depends on the phase of the UV. The components of the grinding force were calculated as the arithmetic mean of their values determined at different vibration phases. The coordinates of the points on the grain movement trajectory corresponding to the change in its operating mode were determined numerically. Numerical simulation of forces using the obtained dependences and experimental study were performed for flat grinding of 12H18N10T steel blanks by the periphery of the circle. The frequency of the superimposed UV is 18.6 kHz; the amplitude of the oscillations in the direction coinciding with the axis of the grinding wheel is 10 microns. To impose vibrations on the workpiece in the course of experimental studies, a device was used in which the workpiece is one of the links of the vibration system. It is established that the difference between the calculated and experimental values of the components of the grinding force is 8 ... 15%. With the imposition of a UV, grinding force is lower by 20 ... 21% than with out their use.

Diagnostics of the presence of a fatigue crack in the compressor blade using the spectrum of vibration amplitudes at the superharmonic resonance

In this study, the solution of the forced vibration response of a structural element with a fatigue crack was carried out using the finite element method to determine the influence of its presence on the flexural forced vibration behaviour of the compressor blade airfoil at the superharmonic resonance of the order 1/2. The blade airfoil with a low twisted angle was used as an object of investigation to perform the computational analysis. Its vibrations in the plane of minimum stiffness were excited by the kinematic displacement of root edge elements. The fatigue crack was modelled as a mathematical cut. Two locations of the crack were investigated – on the leading edge and convex side of the blade airfoil. The nonlinearity due to the intermittent contact of the crack surfaces, which is caused by the opening and closing of the crack during each vibration cycle, was taken into account by solving the contact problem. To quantify this kind of nonlinear dynamic behaviour, the vibration diagnostic parameter was defined as the displacement amplitude ratio of the dominant harmonics at the superharmonic resonance of the order 1/2. Based on the results of the calculations it has been found that regardless of the crack location, the ratio nature is the same for all vibration axes. However, with vibrations in the plane of minimum stiffness, the crack on the convex side of the airfoil has an opening mode propagation, which makes it possible to fix its location due to a sharp change in the ratio of the amplitudes of the dominant harmonics along the corresponding axis.

Combined CFA-AFM Analytical approach for precipitation reaction regarding crystal growth building single and multiple monolayers based on surface area calculation with image surface roughness analysis (unseen surface)

A reaction of Mebeverine hydrochloride (0.03mM) in pure form with sodium nitroprusside (0.07mM) to form OFF White precipitate. A constant feed was used to collect an enough amount in weight for AFM study. Continuous flow injection analysis was conducted as it is the aim of this study to combine FIA with AFM. To elucidate the study of surface morphology. Various parameters of AFM image surface roughness analysis were discussed in relation to the kind of precipitate formed. Skewness, kurtosis, peak-peak, ten peak height, fractal dimension, wavelength, core roughness depth, and reduced valley depth. All these with the four parameter mainly amplitude, hybrid, functional and spetial. Since no previous study of such was conducted; all usual mode of imaging was dealt with i.e., contact, non-contact and intermittent contact was defined. A non contact mode was used in this study. A detailed study of how the crystal growth buildup first mono layer (hypothetical based on the date obtained also how much each grain carry a concentration with the number that are on the first mono layer. Number of given samples of surface area calculation plus a demonstration of the hypothetically formed multi mono layers specially at high reactant concentration. The main aim of this project was the binding of AFM with FIA which is regarded as an new approach which might be a very useful knowledge for other researcher.

A numerical evaluation on nonlinear dynamic response of sandwich plates with partially rectangular skin/core debonding

Abstract As one of the most dangerous defects in the sandwich panel, debonding could significantly degrade load carrying capacity and affect dynamic behaviour. The present work dealt with debonding detection of the rectangular clamped hybrid sandwich plate by using ABAQUS software. The influence of various damage ratios on the linear and nonlinear dynamic responses has been studied. The finite element model was initially validated by comparing the modal response with the experimental test. Rectangular debonding was detected by comparing dynamic responses of free and forced vibrations between intact and debonded models. A wide range of driving frequency excitation corresponding to transient and harmonic concentrated loads was implemented to highlight nonlinear behaviour in the intermittent contact in the debonded models. The results showed that debonding existence contributed to the natural frequency reduction and modes shape change. The numerical results revealed that debonding affected both the steady-state and impulse responses of the debonded models. Using the obtained responses, it was detected that the contact in the debonded region altered the dynamic global response of the debonded models. The finding provided the potential debonding diagnostic in ship structure using vibration-based structural health monitoring.

Repair Delay Analysis of Mobile Storage Systems Using Erasure Codes and Relay Cooperation

Mobile storage systems (MSSs) which store popular content in mobile devices can reduce the heavy traffic burden on the base station (BS). To deal with data loss caused by the mobility of devices, erasure codes are widely used in practice to improve system reliability. The duration to repair all lost data is defined the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">repair delay</i> . However, the repair delay via device-to-device communications is usually large due to intermittent contacts among devices within a given communication range, which causes files to be irreparable and permanently lost. This paper focuses on analyzing the repair delay of the MSSs through D2D communications. We adopt a coded repair process running periodically and derive analytical expressions of the average repair delay by taking into account factors, i.e., limited communication range, device mobility, and coded repair scheme. Moreover, considering that devices need multipath contacts to repair lost data for large files, we propose a relay cooperation repair scheme, in which some mobile devices can act as relay nodes to transmit data cooperatively. Furthermore, we design a heuristic algorithm to optimize the number of relay devices and the amount of data allocated to each path, with the objective of minimizing the average repair delay. We find that maximum distance separable codes can yield smaller average repair delays for small files, and the average repair delay can be reduced by selecting faster moving devices to participate. With the file size increasing, the relay cooperation repair scheme can significantly improve repair efficiency in MSSs using the proposed heuristic algorithm.

Toward a physical model of the clavichord.

String excitation by the tangent in the clavichord is a unique mechanism. The tangent, keeping in contact with the string after the initial strike, continuously controls the string tension. Four main flexible subsystems are considered in the clavichord: the tangent/key subsystem, the string subsystem, the bridge-soundboard subsystem, and the string damper subsystem. A modal description of the dynamics of these subsystems is proposed. Parameters of the subsystems are estimated on a copy of a historical instrument by Hubert (1784). The different subsystems and their couplings are modeled using a modal Udwadia-Kalaba formulation. The string-tangent interaction is modeled via the intermittent contact dynamics, using the Kirchoff-Carrier string model. Realistic string, soundboard, and tangent motions are obtained using a time-domain synthesis scheme that computes the dynamics of the uncoupled subsystems and the constraints resulting from coupling between them. Simulated motions of the model in response to a driving force on the key are analyzed. The results are consistent with experimental measurements and published data on the dynamics of the clavichord. The model is able to reproduce the main acoustic features of the instrument: force on the key for intonation control, key velocity for dynamic nuances control, and constant spectral slope for varying dynamic nuances.

Effects of two different early socialization models on social behavior and physiology of suckling piglets

Early socialization not only facilitates positive behaviors and cognition abilities of post-weaning piglets, but also has effects on social behavior and physiology of suckling piglets during the lactation. Therefore, this study aimed to investigate the effects of early socialization environment on social behavior, stress coping and weaning weight of suckling piglets. We selected 199 piglets (Large White×Duroc×Min pig) from 18 litters and three treatments were differentiated: intermittent contact group (IC, 6 litters), piglets of two neighboring litters were socialized twice a week for 3 h from D14 (14 days of age) to D35; continuous contact group (CC, 6 litters), piglets of two neighboring litters were socialized continuously from D14 to D35; the control group (CON, 6 litters), piglets were not socialized during the lactation. Behavioral observation occurred on D14, D15, D21, D22, D28, D29, D33 and D34, and blood samples were collected on D16, D28 and D34. The results revealed that the amount of fighting and head knocking in IC group was higher than CC and CON groups (P < 0.05). On the social interaction during the lactation, for performing piglet, piglets in CC group showed more oral-nasal contact than IC in 3 weeks of age (W3, D21 and D22) (P = 0.045), and socialized groups (CC, IC) showed more oral-nasal contact than CON in W4 (P = 0.001). The amount of mounting in CC was higher than IC and CON from W3 to W5 (P < 0.001). For receiving pig, amounts of avoiding behavior in IC and CC were higher than CON in W4 (P = 0.047). The return approach (positive response to the performing pig) of IC and CC were higher than C in W2, CC was higher than IC and CON in W3 (P = 0.003), socialized groups were higher than CON in W4 and W5 (P < 0.001). Serum epinephrine concentration in IC and CC were lower than CON on D16 (P < 0.001). The brain-derived neurotrophic factor (BDNF) concentration of IC was higher than CC and CON (P < 0.05) on D16 and D28, IC and CC were higher than CON (P = 0.004) on D34. There was no significant difference in weaning weight and cross-sucking frequency among treatments. In conclusion, the early socialization environment provided opportunities for piglets to improve their social skills, increased the expression of social behaviors and had a positive impact on the expression of BDNF in piglets.

Tuning-fork-based piezoresponse force microscopy

Surface displacements of a few picometers, occurring after application of an electric potential to piezoelectric materials, can be detected and mapped with nanometer-scale lateral resolution by scanning probe methods, the most notable being piezoresponse force microscopy (PFM). Yet, absolute determination of such displacements, giving access for instance to materials’ piezoelectric coefficients, are hindered by both mechanical and electrostatic side-effects, requiring complex experimental and/or post-processing procedures for carrying out reliable results. The employment of quartz tuning-fork force sensors in an intermittent contact mode PFM is able to provide measurements of electrically-induced surface displacements that are not influenced by electrostatic side-effects typical of more conventional cantilever-based PFM. The method is shown to yield piezoeffect mapping on standard ferroelectric test crystals (periodically-poled lithium niobate and triglycine sulfate), as well as on a ferroelectric polymer (PVDF), with no visible influence from the applied dc electric potential.

Crocodylian swim tracks from the Gates Formation (Albian), British Columbia, Canada: comparisons with Cretaceous crocodylian ichnology in western USA

Numerous crocodylian swim tracks occur in the late Early Cretaceous and earliest Late Cretaceous of western North America, in coastal plain deposits marginal to the Cretaceous interior seaways. New assemblages from the lower Albian Gates Formation, within the Tumbler Ridge UNESCO Global Geopark Quintette site (TRUGG-Q) in British Columbia, Canada, resemble those from Albian-Cenomanian Dakota Sandstone sites in Colorado, Kansas and Utah, and facilitate comparative analysis of how such assemblages are registered and preserved. The Gates Formation track assemblage formed on the southwest margin of the ‘Moosebar Sea’ that filled the foredeep of the Western Canada Foreland Basin in the Early Albian. Northeast-prograding sandy deltas were backed by low-lying and heavily-vegetated coastal plains, inhabited by track-making dinosaurs, birds, and crocodylians. The base of a tidal channel-fill at the TRUGG-Q site preserves crocodylian swim traces indicating progression largely parallel to the channel axis, as also inferred for some USA sites. Swim track lengths can be categorized on a short–long spectrum which reflects swimming behavior, with short, wide toe tip traces indicating firm digging-in of toes (‘punting’ or ‘poling’ behavior), and elongate scrape marks indicating light touch-down (or substrate ‘raking’) by buoyant animals making intermittent contact with a subaqueous substrate. The body lengths size of crocodylian trackmakers can be calculated from rare complete ‘walking’ track footprints or from the widths, not lengths, in the case of ‘swim’ traces. The mean size of the Canadian tracks indicates individuals with body lengths in the range of ~1.0 m, with larger trackmakers up to ~4.0 m more common at the USA sites.

B-PO04-208 A TELEMETRY ALARM: WHEN THE PACEMAKER IS SILENCED BY THE NOISE

Accurate ventricular sensing is necessary for appropriate delivery of pacing and shocks. Ventricular oversensing can cause failure to pace in a pacer dependent patient. We describe a case of lead-device interaction causing oversensing and failure to pace after ventricular septal defect (VSD) occluder device placement. To our knowledge, this is the first report of lead-device interference with a VSD occluder device. N/A A 60 year old man with chronic stage D systolic heart failure, LVAD, and VSD underwent percutaneous VSD repair with an Amplatzer VSD occluder. In the immediate post-procedure period, he became bradycardic despite having an ICD with programmed brady-therapy. Device interrogation demonstrated normal impedance, sensing, and pacing parameters, but also revealed intermittent noise on both channels the near-field and the shock channel causing oversensing. Presence of noise on both channels was more consistent with device-device interaction than lead fracture. Fluoroscopic images revealed intermittent contact between the RV lead and VSD occluder. Adjustment of sensitivity, refractory, and blanking periods was not effective. As a temporizing solution, the ICD was placed in asynchronous mode, acutely improving the heart rate. The RV lead was revised, resolving the clinical problem. Device-device interactions are rare but can be a result of lead-lead chatter or mechanical interference with other intracardiac devices such as retained fragments, or in this case, a VSD occluder device. As structural interventions become more prevalent, electrophysiologists need to be aware of lead-device interactions.

Bilinear Systems With Initial Gaps Involving Inelastic Collision: Forced Response Experiments and Simulations

Abstract In this paper, the forced response of a two degrees-of-freedom (DOF) bilinear oscillator with initial gaps involving inelastic collision is discussed. In particular, a focus is placed upon the experimental verification of the generalized bilinear amplitude approximation (BAA) method, which can be used for the accurate estimation of forced responses for bilinear systems with initial gaps. Both experimental and numerical investigations on the system have been carried out. An experimental setup that is capable of representing the dynamics of a 2DOF oscillator has been developed, and forced response tests have been conducted under swept-sine base excitation for different initial gap sizes. The steady-state response of the system under base excitation was computed by both traditional time integration and BAA. It is shown that the results of experiments and numerical predictions are in good agreement especially at resonance. However, slight differences in the responses obtained from both numerical methods are observed. It was found that the time duration where the DOFs are in contact with each other predicted by BAA is longer than that predicted by time integration. Spectral analyses have also been conducted on both experimental and numerical results. It was observed that in a frequency range where intermittent contact between the masses occurs, super-harmonic components of the excitation frequency are present in the spectra. Moreover, as the initial gap size increases, the frequency band where the super-harmonic components are observed decreases.

Astrocytes-derived extracellular vesicles in motion at the neuron surface: Involvement of the prion protein.

Astrocytes‐derived extracellular vesicles (EVs) are key players in glia‐neuron communication. However, whether EVs interact with neurons at preferential sites and how EVs reach these sites on neurons remains elusive. Using optical manipulation to study single EV‐neuron dynamics, we here show that large EVs scan the neuron surface and use neuronal processes as highways to move extracellularly. Large EV motion on neurites is driven by the binding of EV to a surface receptor that slides on neuronal membrane, thanks to actin cytoskeleton rearrangements. The use of prion protein (PrP)‐coated synthetic beads and PrP knock out EVs/neurons points at vesicular PrP and its receptor(s) on neurons in the control of EV motion. Surprisingly, a fraction of large EVs contains actin filaments and has an independent capacity to move in an actin‐mediated way, through intermittent contacts with the plasma membrane. Our results unveil, for the first time, a dual mechanism exploited by astrocytic large EVs to passively/actively reach target sites on neurons moving on the neuron surface.

Higher incidence of headache in patients with intermittent mucosal contact points between the septum and lateral nasal wall.

IntroductionThe nasal mucosal contact points between the two opposing mucosal surfaces leading to the headache had been a point of debate for many years; the intermittent and fixed contact points and their relationship with headache have never been investigated before. We have studied the relationship of headache with a different type of contact points in our study.ObjectivesThe aim of our study was to study two different types of mucosal contact point between the lateral nasal wall and the nasal septum and to study their relationship with symptom of headache.There have been many papers published related to the mucosal contact points in the nose and their relationship with headache, most of the published data did not find any relation between the headache and the mucosal contact points. We conducted a retrospective study of 116 patients with deviated nasal septum and contact point with the lateral nasal wall.MethodsA retrospective study done at a tertiary institute Included 116 CT scan of paranasal sinuses showing the deviated nasal septum with mucosal contact points, 64 CT scan showed severe deviated nasal septum with fixed contact points between the septum and the inferior turbinate, other 52 scans showed the intermittent mucosal contact point, that is, septum is coming in contact with inferior turbinate only when turbinate is enlarged.ResultsThirteen patients out of 64 patients (20.31%) had a headache in the fixed contact point group as compared to 20 out of 52 (38.46%) patients in the intermittent mucosal contact points group; post‐surgery, the 17/20 patients improved in the intermittent mucosal contact points group as compared to 5/13 in fixed contact points group.ConclusionsWe conclude that the overall incidence of headache associated with mucosal contact points is low but the higher association is seen in the intermittent contact group.Level of Evidence4.

Difference between the cell wall roughnesses of mothers and daughters of Saccharomyces cerevisiae subjected to high pressure stress

High hydrostatic pressure (HHP) stress generates cellular responses similar to those to other stresses that yeasts endure in fermentation tanks. Structural and spatial compaction of molecules, as well as weakening and stretching of plasma membranes and cell walls, are often observed and have a significant influence on the fermentative process. Atomic force microscopy (AFM) yields accurate data on the morphological characteristics of yeast cell walls, providing important insights for the development of more productive yeast strains. Saccharomyces cerevisiae cell wall assessment using AFM in the intermittent contact reading mode using a silicon cantilever, before and after application of a pressure of 100 MPa for 30 min, demonstrated that mother and daughter cells have different responses. Daughter cells were more sensitive to the effects of HHP, presenting lower average Ra (arithmetic roughness), Rz (ten-point average roughness), and Rq (root-mean-square roughness) after exposure to high pressure. Better adaptation to stress in mother cells leads to higher cell wall resistance and, therefore, to better protection.

Evaluation of Opportunistic Service Provisioning with Ordered Chaining

Opportunistic Mobile Networks (OMNs) enable communication among the otherwise disconnected devices via intermittent contacts. Based on this premise, the paradigms of Opportunistic Computing (OC) and Opportunistic Service Provisioning (OSP) were proposed, where a user can request remotely available hardware and software services from the relevant nodes that are not in direct contact with the user's device. In this work, we consider the problem of OSP together with ordered chaining. Chaining (or composition) refers to the scenario where two or more services must be availed by a given data object one after the another, for example, translating a text file and converting it to another format. Such a chaining is termed as ordered when the required services must be availed in a specific sequence. We discuss four schemes for achieving OSP with ordered chaining. One of the proposed schemes unicasts the OSP request messages, while another one adapts a popular unicasting algorithm for OMNs. The third scheme is based on flooding, whereas in the final one, nodes replicate requests only to those who provide the concerned services. The results of performance evaluation using real-life traces and synthetic mobility models show that up to about 99 percent of the service requests can be satisfied. The results also indicate that unicasting is rather unsuitable to achieve OSP.

Insights on the continuous representations of piecewise-smooth nonlinear systems: limits of applicability and effectiveness

Dynamical systems subject to intermittent contact are often modeled with piecewise-smooth contact forces. However, the discontinuous nature of the contact can cause inaccuracies in numerical results or failure in numerical solvers. Representing the piecewise contact force with a continuous and smooth function can mitigate these problems, but not all continuous representations may be appropriate for this use. In this work, five representations used by previous researchers (polynomial, rational polynomial, hyperbolic tangent, arctangent, and logarithm-arctangent functions) are studied to determine which ones most accurately capture nonlinear behaviors including super- and subharmonic resonances, multiple solutions, and chaos. The test case is a single-DOF forced Duffing oscillator with freeplay nonlinearity, solved using direct time integration. This work intends to expand on past studies by determining the limits of applicability for each representation and what numerical problems may occur.

Force Reconstruction at Mechanical Interfaces Using a Modal Filtering Decomposition Approach

Traditional approaches to analyzing nonlinear systems often involve assuming a specific model form and model order for the nonlinearity. These nonlinearities in a system could instead be modeled as a nonlinear force applied to an underlying linear system. Force reconstruction methods can be used to recreate this nonlinear force from measured data, allowing the system change to be quantified. A modal based force reconstruction technique has proven capable of recreating force inputs at unmeasured locations and has been successfully applied to nonlinear intermittent external contact forces in previous studies. To extend these findings, a two-beam system was designed such that intermittent contact occurs near the joint locations, resulting in correlated forces. Previous work with this methodology has not addressed correlated loading conditions, so this work extends these techniques to the localization of correlated forces beyond measured points. The methodology is first demonstrated using analytical case studies, then performed experimentally. Acceleration responses are obtained from a sparse measurement grid which does not include the contact points, so the forces are reconstructed at unmeasured locations. Estimates of the nonlinear contact forces are calculated using the force reconstruction process, which are then compared to the measured force values. Cases are presented which address intermittent contact, loosening of preloaded connections, and the reconstruction of multiple connections simultaneously. Reconstructing correlated forces beyond measured points allows for the ability to locate and estimate forces without needing to assume the locations of these forces prior to acquiring data, extending the range of applications for these techniques.