Made-in-transit (MIT) is a supply chain concept for the complete or partial manufacturing or production of perishable foods while being transported to the market. A 33 factorial design was carried out looking at the fermentation temperature (25°C, 30°C, and 35°C), apple fiber concentration (0%, 0.5%, 1.0%, and 1.5% v/w), and experimental treatment (no vibration or vibration to mimic that associated with transportation). Yogurt was manufactured using one of the four apple fiber concentrations and then fermented under one of the three fermented temperatures for 48 hours before being shifted into a 4°C cold room to finalize the gelling process. Physical-chemical properties including titratable acidity, pH, whey syneresis, and texture analysis were analyzed for all conditions using two-way ANOVA. There were noticeable differences between the fermentation temperature and the experimental treatment on the physical-chemical and sensory attributes measured. The apple fiber had no impact. A total of 63 people participated in a hedonic testing study to look at the impact the fermentation temperature, apple concentration, and the experimental treatment had on the appearance, aroma, taste, and mouthfeel of the yogurt. Consumers found the MIT yogurt to be unacceptable based upon all attributes tested (appearance, aroma, flavor, and mouthfeel).

This work compares viscous and structural damping in a lumped-parameter model of a piezoelectric vibration energy harvester. The dynamic response and power harvested are solved in closed-form for devices with combined viscous and structural damping. The results are then reduced to get expressions for isolated cases of viscous and structural damping. The conditions that maximize the power harvested are determined. These devices generally have two maxima. One maximum is not sensitive to the damping model. The other maximum, however, has meaningful differences between viscous and structural damping models. The differences between the two models increase with increasing electromechanical coupling. (C) 2018 Elsevier Ltd. All rights reserved.

This study investigates the vibration of a rotating piezoelectric device that consists of a proof mass that is supported by elastic structures with piezoelectric layers. Vibration of the proof mass causes deformation in the piezoelectric structures and voltages to power the electrical loads. The coupled electromechanical equations of motion are derived using Newtonian mechanics and Kirchhoff's circuit laws. The free vibration behavior is investigated for devices with identical (tuned) and nonidentical (mistuned) piezoelectric support structures and electrical loads. These devices have complex-valued, speed-dependent eigenvalues and eigenvectors as a result of gyroscopic effects caused by their constant rotation. The characteristics of the complex-valued eigensolutions are related to physical behavior of the device's vibration. The free vibration behaviors differ significantly for tuned and mistuned devices. Due to gyroscopic effects, the proof mass in the tuned device vibrates in either forward or backward decaying circular orbits in single-mode free response. This is proven analytically for all tuned devices, regardless of the device's specific parameters or operating speed. For mistuned devices, the proof mass has decaying elliptical forward and backward orbits. The eigenvalues are shown to be sensitive to changes in the electrical load resistances. Closed-form solutions for the eigenvalues are derived for open and close circuits. At high rotation speeds these devices experience critical speeds and instability.

Strawberries are a popular fruit with a pleasing color and flavor. However, its delicate tissue and high sugar content makes it highly perishable with visible mold. In this study, we have attempted to test feasibility of a new edible coating for extending shelf life of ‘Chandler’ strawberries subjected to simulated vibrations of local transportation. Six types of coatings were compared based on the quality of treated berries. Curcumin and limonene were used as natural antimicrobials and coatings were prepared from their liposomes and were over-coated with methyl cellulose. One set of each coating type were subjected to the simulated vibration of local transportation. The vibrated samples had lower shelf life than non-vibrated samples, indicating a robust coating which remains intact during road vibrations is required. Based on the number of berries with visible mold, limonene liposomes showed significantly lower fungal growth compared to the control on the 14th day of storage. Titratable acidity and total phenolic contents were also found to be higher in limonene coated strawberries compared to other coatings. Further study is suggested to test liposome coatings of limonene with different particle size to improve integrity of the coatings when strawberries are subjected to local transportation.

This study investigates the vibration of and power harvested by typical electromagnetic and piezoelectric vibration energy harvesters when applied to vibrating host systems that rotate at constant speed. The governing equations for these electromechanically coupled devices are derived using Newtonian mechanics and Kirchhoff's voltage law. The natural frequency for these devices is speed-dependent due to the centripetal acceleration from their constant rotation. Resonance diagrams are used to identify excitation frequencies and speeds where these energy harvesters have large amplitude vibration and power harvested. Closed-form solutions are derived for the steady-state response and power harvested. These devices have multifrequency dynamic response due to the combined vibration and rotation of the host system. Multiple resonances are possible. The average power harvested over one oscillation cycle is calculated for a wide range of operating conditions. Electromagnetic devices have a local maximum in average harvested power that occurs near a specific excitation frequency and rotation speed. Piezoelectric devices, depending on their mechanical damping, can have two local maxima of average power harvested. Although these maxima are sensitive to small changes in the excitation frequency, they are much less sensitive to small changes in rotation speed.

Hydraulic bushings or mounts are commonly used in automotive suspension and powertrain systems to improve vehicle vibration and structure-borne noise features while influencing ride and handling properties. This article aims to analytically examine certain features of hydraulic suspension bushing designs using frequency domain models. First, a linear time-invariant model of a hydraulic bushing with an inertia track is used to examine the dynamic stiffness (magnitude and loss angle) performance up to about 60 Hz with a given excitation amplitude. Second, the effect of inertia track parameters on dynamic stiffness is examined, and the key differences between fluid-filled suspension bushing and hydraulic engine mount are investigated by comparing the fluid chamber compliance ratios. Finally, the frequency dependence of inertia track parameters is analyzed with a quasi-linear model and the measurements of a laboratory prototype device.

Hydraulic bushings are widely employed in vehicle suspension and sub-frame systems to control motion, and isolate noise and vibration. Although such devices exhibit significant excitation-profile-dependent dynamic properties, prior literature mainly focused on linear system analyses. Thus, this article examines the nonlinear characteristics of common hydraulic bushing configurations. First, a nonlinear model for a bushing with long and short passages in parallel is developed using a lumped parameter approach. Then the system parameters and nonlinearities of a laboratory prototype are identified using experiments and finite element tools, with an emphasis on the characterization of the flow passages. Steady state harmonic and transient step experiments are conducted on the prototype, and the pressures inside two fluid chambers and the force transmitted to the base are measured. Solutions of the nonlinear model show that the proposed model can well predict both steady state sinusoidal and transient responses for either single or multi-passage configurations. INTRODUCTION A typical hydraulic bushing usually consists of inner and outer metal sleeves, a rubber element, and two hydraulic chambers filled with anti-freeze and water mixture [1-6]. The two chambers are usually connected by one or more flow passages which communicate fluid between two chambers when a relative deflection of the inner and outer metal sleeves causes pressures to vary. Although hydraulic bushings exhibit significant frequency-dependent and amplitude-sensitive properties, prior articles essentially employed linear system theory to examine their spectral characteristics [1-5]. Therefore, specific objectives of this paper are as follows: (1) Formulate the nonlinear model of common fluid-filled bushing configurations, and identify fluid passage nonlinearities via experiments on a laboratory prototype; and (2) Validate the nonlinear model by comparing harmonic and transient response predictions with measurements. NONLINEAR FLUID SYSTEM MODEL The fluid model for a bushing with parallel long and short flow passages is developed in Fig. 1. The hydraulic elements are represented by several control volumes, and incompressible flow is assumed. Note that the internal long fluid passage (#i, the inertia track) is shown as external tubing for the sake of clarity. Static and dynamic displacement excitations are applied to the inner metal part while the outer metal sleeve is fixed relative to the inner sleeve. The rubber element (#r) is represented by a Kelvin-Voigt model with excitation displacement-dependent rubber stiffness kr(x) and viscous damping coefficient cr(x). The two fluid chambers (#1 and #2) are described by nonlinear compliance elements C1(p1) and C2(p2), respectively, with effective pumping areas A1 and A2. The fluid passages are represented by nonlinear fluid inertances Ii(qi) and Is(qs) and nonlinear fluid resistances Ri(qi) and Rs(qs), respectively, where q is the volumetric flow rate. Note that Ri and Rs also include the minor momentum losses at the tube fittings and bends, etc. [7]. The dynamic displacement excitation x(t), from the static equilibrium, is applied to the bushing (under a mean load fm ). By applying the momentum and continuity equations to each flow passage and two fluid chambers, the following equations are obtained: 1 2 ( ) ( ) ( ) ( ) ( ) ( ) i i i i i i p t p t I q q t R q q t − = +  , (1a) 1 2 ( ) ( ) ( ) ( ) ( ) ( ) s s s s s s p t p t I q q t R q q t − = +  , (1b) 1 1 1 1 ( ) ( ) ( ) ( ) ( ) s i A x t q t q t C p p t − − − =   , (1c) 2 2 2 2 ( ) ( ) ( ) ( ) ( ) i s A x t q t q t C p p t + + =   . (1d) 1 Copyright © 2015 by ASME Here, qi(t) and qs(t) are the dynamic volumetric flow rates through long track and short passages, and p1(t) and p2(t) are the dynamic pressures inside the two fluid chambers, respectively. When only one passage is used, say a long inertia track, the governing equations for that configuration are obtained by setting qs(t) = 0 and Rs→∞. Figure 1. NONLINEAR FLUID SYSTEM MODEL OF A HYBRAULIC BUSHING. With respect to the total dynamic force transmitted to the outer sleeve, fT(t) is divided into the rubber (subscript r) and hydraulic (subscript h) paths: T Tr T m h ( ) ( ) ( ) f t f f t f t = + + , Tr ( ) ( ( ) ( ( ) ) ) r r f t k x x t c x x t = +  , Th 2 2 1 1 ( ) ( ) ( ) f t A p t A p t = − . (2a-c) EXPERIMENTAL STUDIES A laboratory device, as described in our prior article [4], is utilized to characterize bushing nonlinearities. This device consists of two similar chambers filled with water and a customized mid-plate which accommodates external long and short flow passages. To simulate typical real life fluid-filled bushing designs, three configurations of the prototype, as illustrated in Fig. 2 (a) to (c), are evaluated. First, configuration B1 is investigated when the two hydraulic chambers are connected by only one long passage. Second, B2 configuration is examined when the long passages are closed and the short passage orifice is fully open. Finally, the combination of long and short passages in parallel is examined by using B3 configuration; refer to [4] for more details. The steady state sinusoidal experiments are first conducted on the above mentioned configurations using a non-resonant elastomer test machine (MTS 831.50, [8]). A sinusoidal displacement excitation x(t) = Ax sin 2πft is applied to the prototype device under a mean load, where Ax is the zero to peak amplitude, and f is the excitation frequency (Hz). The transmitted force fT(t) and dynamic pressure inside two chambers, p1(t) and p2(t), are measured from 1 to 60 Hz with 1 Hz increment under two amplitudes, X = 0.1 and 1.0 mm, where X = 2Ax is the peak to peak (p-p) value. Significant amplitude and frequency dependence is observed from the measured dynamic stiffness spectra for B1, B2, and B3 configurations with X = 0.1 and 1.0 mm. Next, a step-up and step-down displacement excitation is also applied to the prototype device under a mean load. Measurements of transient responses imply that the dynamic responses highly depend on the step excitation amplitude. Accordingly, the nonlinear system parameters must be identified to model the excitation profile dependent properties. Figure 2. CONFIGURATIONS OF THE HYDRUALIC BUSHING CONSTRUCTED FOR LABORATORY STUDIES. (a) CONFIGURATION B1 WITH LONG FLUID PASSAGE OF DIAMETER di; (b) CONFIGURATION B2 WITH SHORT FLOW PASSAGE WITH RESTRICTION DIAMETER do; (c) CONFIGURATION B3 WITH PARALLEL LONG AND SHORT FLOW PASSAGES. IDENTIFICATION OF SYSTEM PARAMETERS The rubber path is approximated by the Kelvin-Voigt model, rubber stiffness and viscous damping elements kr (ω, X) and cr(X) are estimated by interpolating measured dynamic stiffness of a bushing with fluid drained. In order to estimate C1 or C2, a laboratory experiment is carried out to measure a change in chamber internal volume (ΔV) due to an incremental pressure (Δp). Then the fluid compliance around an operating point (o) is estimated as C ≈ ∆V/∆p|o. It is observed from measured ΔV vs. Δp data that as the pressure is increased from 0 to around 180 kPa, ∆V/∆p variation is less than 15%. Therefore, C1 and C2 are assumed to be linear, and their values are estimated based on a linear polynomial fit of measurements. The effective pumping areas A1,2 are examined next by employing a structural finite element code. Results show that a variation of A1,2 is less than 3% when the load is varied from 100 to 1000 N. Thus, A1,2 values are also assumed to be constant. Inertance of long and short passages is calculated as Ii = ρli/Ai and Is = ρls/As by assuming unsteady turbulent flow [9]. A bench experiment is conducted to measure the steady flow rate (q) through each fluid passage under a pressure differential (∆p, range from 6.9 to 206.8 kPa). Experimental (a) (b)

Fluid-filled bushings with tunable stiffness and damping properties are now employed in vehicles to improve ride characteristics and to reduce vibration and noise. Since scientific literature on this topic is sparse, a bushing prototype which can provide various combinations of long and short flow passages is designed and built. Several common fluid-filled bushing configurations are experimentally examined for their dynamic stiffness and pressure spectra. Linear time-invariant models (with lumped fluid elements) are proposed for a hydraulic bushing with two parallel flow passages. Next, a model with only a long capillary tube passage (an inertia track) is examined. Further, peak magnitude and loss angle frequencies are analytically found. Several methods for the identification of bushing parameters (up to 50Hz) are suggested. The linear models are validated by comparing predictions with measured stiffness magnitude and loss angle spectra. Finally, the principal features of a practical device are diagnosed using analytical models and measurements for two excitation amplitudes.

Hydraulic bushings, which are often employed in vehicle suspension systems, exhibit significant excitation-dependent properties. However, previous analyses were mainly based on the linear system theory. To overcome this void, nonlinear characteristics of common hydraulic bushing configurations are examined in this article, with focus on the component properties as excited by sinusoidal or step displacements of various amplitudes. First, a nonlinear model for a laboratory prototype with a long passage and a short passage (in parallel) is developed using a lumped-parameter approach. Then the system parameters and nonlinearities are identified using experimental and computational methods, with an emphasis on characterization of the flow passage resistances. Steady-state harmonic and transient step experiments are conducted on the prototype, and the dynamic pressures inside two fluid chambers and the force transmitted to the base are measured. Numerical solution of the nonlinear model shows that the proposed model predicts both steady-state sinusoidal responses and transient responses well for single-passage and dual-passage configurations; significant improvement over a corresponding linear model is observed. Finally, approximate analytical and semi-analytical solutions of the nonlinear model are obtained by using the harmonic balance method.

Hydraulic bushings are commonly employed in vehicle suspension and body sub-frame systems to control motion, vibration, and structure-borne noise. Since literature on this topic is sparse, a controlled bushing prototype which accommodates a combination of long and short flow passages and flow restriction elements is first designed, constructed and instrumented. Step-up and step-down responses of several typical fluid-filled bushing configurations are measured along with steady harmonic time histories of transmitted force and internal pressures. To analyze the experimental results and gain physical insights into the hydraulic bushing system, lumped system models of bushings with different design features are developed, and analytical expressions of transmitted force and internal pressure responses are derived by using the convolution method. Parametric studies are also conducted to examine the effect of hydraulic element parameters. System parameters are successfully estimated for both harmonic and step responses using theory and measurements, and the dynamic force measurements are analyzed using analytical predictions. Finally, some nonlinearities of the system are also observed, and the fluid resistance of flow passage is found to be the most nonlinear element.

Fluid filled bushings are commonly used in vehicle suspension and sub-frame systems due to their spectrally-varying and amplitude-dependent properties. Since the literature on this topic is sparse, a controlled laboratory prototype bushing is first designed, constructed, and instrumented. This device provides different internal combination of long and short flow passages and flow restriction elements. Experiments with sinusoidal displacement excitations are conducted on the prototype, and dynamic stiffness spectra along with fluid chamber pressure responses are measured. The frequencydependent properties of several commonly seen hydraulic bushing designs are experimentally studied and compared under two excitation amplitudes. Further, new linear time-invariant models with one long and one short flow passages (in parallel or series) are proposed along with the limiting cases. The analytical models are validated in frequency and time domains using transmitted force and chamber pressure measurements. The proposed formulation provides insights into various performance features.

Hydraulic bushings are widely used in vehicle applications, such as suspension and sub-frame systems, for motion control and noise and vibration isolation. To study the dynamic properties of such devices, a controlled laboratory bushing prototype is designed and fabricated. This device has the capability of varying different combinations of long and short flow passages and flow restriction elements. Transient experiments with step-up and step-down excitations are conducted on the prototype, and the transmitted force responses are measured. The transient properties of several commonly seen hydraulic bushing designs are experimentally studied. Analytical models for bushings with different design features are developed based on the linear system theory. System parameters are then estimated for step responses based on theory and measurements. Finally, the linear models are utilized to analyze the step force measurements, from which some nonlinearities of the bushing system are identified.