Shaker System Research Articles

Note: A kinematic shaker system for high amplitude, low frequency vibration testing.

This note describes a shaker system capable of high peak-velocity, large amplitude, low frequency, near-sinusoidal excitation that has been constructed and employed in experiments on the inhibition of Rayleigh-Bénard convection using acceleration modulation. The production of high peak-velocity vibration is of interest in parametric excitation problems of this type and reaches beyond the capabilities of standard electromagnetic shakers. The shaker system described employs a kinematic linkage to two counter-rotating flywheels, driven by a variable-speed electrical motor, producing peak-to-peak displacements of 15.24 cm to a platform mounted on two guide rails. In operation, this shaker has been demonstrated to produce peak speeds of up to 3.7 m/s without failure.

Computational modeling of shear forces and experimental validation of endothelial cell responses in an orbital well shaker system

Vascular endothelial cells are continuously exposed to hemodynamic shear stress. Intensity and type of shear stress are highly relevant to vascular physiology and pathology. Here, we modeled shear stress distribution in a tissue culture well (R = 17.5 mm, fill volume 2 ml) under orbital translation using computational fluid dynamics with the finite element method. Free surface distribution, wall shear stress, inclination angle, drag force, and oscillatory index on the bottom surface were modeled. Obtained results predict nonuniform shear stress distribution during cycle, with higher oscillatory shear index, higher drag force values, higher circular component, and larger inclination angle of the shear stress at the periphery of the well compared with the center of the well. The oscillatory index, inclination angle, and drag force are new quantitative parameters modeled in this system, which provide a better understanding of the hydrodynamic conditions experienced and reflect the pulsatile character of blood flow in vivo. Validation experiments revealed that endothelial cells at the well periphery aligned under flow and increased Kruppel-like Factor 4 (KLF-4), cyclooxygenase-2 (COX-2) expression and endothelial nitric oxide synthase (eNOS) phosphorylation. In contrast, endothelial cells at the center of the well did not show clear directional alignment, did not induce the expression of KLF-4 and COX-2 nor increased eNOS phosphorylation. In conclusion, this improved computational modeling predicts that the orbital shaker model generates different hydrodynamic conditions at the periphery versus the center of the well eliciting divergent endothelial cell responses. The possibility of generating different hydrodynamic conditions in the same well makes this model highly attractive to study responses of distinct regions of the same endothelial monolayer to different types of shear stresses thereby better reflecting in vivo conditions.

Detection of Blade Mistuning in a Low Pressure Turbine Rotor Resulting from Manufacturing Tolerances and Differences in Blade Mounting

For a serious prediction of vibration characteristics of any structure, a detailed knowledge of the modal characteristic is essential. This is especially important for bladed turbine rotors. Mistuning of the blading of a turbine rotor can appear due to manufacturing tolerances or because of the blading process itself due to unequal mounting of the blades into the disk. This paper investigates the mistuning of the individual blades of a low pressure turbine with respect to the effects mentioned above. Two different rotors with different aerodynamic design of the blades were investigated. The blades were mounted to the disk with a so-called hammer head root which is especially prone to mounting irregularities. For detailed investigations, the rotor was excited with a shaker system to detect the forced response behavior of the individual blades. The measurements were done with a laser vibrometer system. As the excitation of rotor structure was held constant during measurement, it was possible to detect the line of nodes and mode shapes as well. It could be shown that the assembly process has an influence on the mistuning. The data were analyzed and compared with numerical results. For this, different contact models and boundary conditions were used. The above described characterization of modal behavior of the rotor is the basis for the upcoming aeroelastic investigations and especially for the blade vibration measurements of the rotor, turning with design and off-design speeds.

Aggregate-based human pluripotent stem cell manufacturing with the ambr®15 platform

Human pluripotent stem cells (hPSCs) are a promising cell source for many biomedical applications including cell replacement therapy and drug screening. As such, robust and scalable hPSC manufacturing processes are needed to produce appropriate quantities of high quality hPSCs. Various processes have been proposed, but none are fully characterised and optimised. CCRM has undertaken the task of developing and characterising an efficient and robust aggregate-based hPSC manufacturing process in stirred-tank reactors (STRs). Here we present an hPSC aggregate culture process that has been translated from an orbital shaker system to the ambr®15 platform (Sartorius Stedim), a microscale and controlled STR system. With this process, aggregates can be consistently formed from a single cell suspension in the ambr®15 within 24 hours. These aggregates are 41% smaller than those formed on an orbital shaker, but can achieve 1.5 times greater cell expansion over a 4-day period. Over 75% of the hPSCs produced co-express the pluripotent markers Oct4, Nanog, Sox2 and SSEA4; however, on average, 6% more expression is observed in the hPSC product from the ambr®15. Strategies for routine passaging of the cells are being explored. The ambr®15 is capable of parallel processing and multi-parametric control of 24 bioreactors; thereby enabling the exploration of individual and interacting effects of multiple operating parameters on hPSC culture performance. We have begun to explore the effects of 5 operating parameters on aggregate size and size variability using one-factor-at-a-time and split-plot factorial design experiments. As aggregate size was observed to influence hPSC differentiation trajectory, an understanding of how to control and manipulate aggregation dynamics will allow us to tailor our process for specific end applications. Efficient small-scale studies enabled by the ambr®15 will ultimately be translated to larger scale STR systems for robust and routine production of hPSC.

Spiral electrode d33 mode piezoelectric diaphragm combined with proof mass as energy harvester

The paper demonstrates an energy harvester using a freestanding piezoelectric diaphragm combined with a proof mass. The diaphragm bearing double-sided spiral electrodes makes use of the d33 piezoelectric effect to realize energy scavenging. The harvester was fabricated by using a MEMS technique. The energy converting performance of the diaphragm was characterized by a shaker system. Proof masses were combined at the center of the diaphragm to tune the resonance of the harvester for the sake of scavenging low frequency vibrational energy. A receptance model was built to explain the vibrational behavior of the combined system. The resonance tuning and energy harvesting performance of the combination system was experimentally verified.

Development of high‐performance shake tables using the hierarchical control strategy and nonlinear control techniques

SummaryConventional shake tables employ linear controllers such as proportional‐integral‐derivative or loop shaping to regulate the movement. However, it is difficult to tune a linear controller to achieve accurate and robust tracking of different reference signals under payloads. The challenges are mainly due to the nonlinearity in hydraulic actuator dynamics and specimen behavior. Moreover, tracking a high‐frequency reference signal using a linear controller tends to cause actuator saturation and instability. In this paper, a hierarchical control strategy is proposed to develop a high‐performance shake table. A unidirectional shake table is constructed at the University of British Columbia to implement and evaluate the proposed control framework, which consists of a high‐level controller and one or multiple low‐level controller(s). The high‐level controller utilizes the sliding mode control (SMC) technique to provide robustness to compensate for model nonlinearity and uncertainties experienced in experimental tests. The performance of the proposed controller is compared with a state‐of‐the‐art loop‐shaping displacement‐based controller. The experimental results show that the proposed hierarchical shake table control system with SMC can provide superior displacement, velocity and acceleration tracking performance and improved robustness against modeling uncertainty and nonlinearities. Copyright © 2015 John Wiley & Sons, Ltd.

A Microcontroller Approach to Measuring Transmissibility of MEMS Devices

The transmissibility reveals two very useful characteristics of a micro-electro-mechanical systems (MEMS) device, the resonant frequency and the mechanical quality factor. Real time knowledge on these two important factors can enhance application performance or avoid potential problems from environmental disturbances due to fabrication tolerances and the resulting operational differences in otherwise identical devices. Expensive laboratory equipment is typically used to measure the transmissibility. However, these test systems are not readily adaptable to field use. Therefore, it is important to be able to measure the transmissibility using a real time technique with a simplified test setup. This study proposes a technique that can compute the transmissibility in real time using a low cost microcontroller. This technique utilizes two laser vibrometers to detect the input and output motions of the proof mass in a MEMS device, which are fed to high speed 500 KHz analog to digital converters (ADC) in the microcontroller. A filtering step is performed to decrease noise. After the sampling and pre-filtering, a Fast Fourier Transform (FFT) is performed to convert the time-domain signals to frequency domain signals. The amplitude of the output signal at each frequency is divided by the amplitude of the corresponding input signal at each frequency to obtain the transmissibility. To overcome the difficulties resulting from measurement and quantization noise, a recursive calculating algorithm and a de-quantization filter are introduced. The recursive calculating process guarantees that the system updates the results continually, which results in a transmissibility plot covering the entire bandwidth. The de-quantization filter considers the validity of the data and performs the transmissibility division step accordingly. A cantilevered structure was chosen as the device-under-test to verify and evaluate this technique. The cantilevered device was attached to an electromechanical shaker system for vibratory stimulation. Two laser vibrometers were used to detect the input and output motion and this data was fed into a microcontroller. The microcontroller was STM32F407, which is 32-bit and 168 MHz controller. The tests demonstrated that this technique can measure the transmissibility and therefore the resonant frequency and mechanical quality factor accurately compared to a professional signal analyzer.

Cross Talk between NOTCH Signaling and Biomechanics in Human Aortic Valve Disease Pathogenesis.

Aortic valve disease is a burgeoning public health problem associated with significant mortality. Loss of function mutations in NOTCH1 cause bicuspid aortic valve (BAV) and calcific aortic valve disease. Because calcific nodules manifest on the fibrosa side of the cusp in low fluidic oscillatory shear stress (OSS), elucidating pathogenesis requires approaches that consider both molecular and mechanical factors. Therefore, we examined the relationship between NOTCH loss of function (LOF) and biomechanical indices in healthy and diseased human aortic valve interstitial cells (AVICs). An orbital shaker system was used to apply cyclic OSS, which mimics the cardiac cycle and hemodynamics experienced by AVICs in vivo. NOTCH LOF blocked OSS-induced cell alignment in human umbilical vein endothelial cells (HUVECs), whereas AVICs did not align when subjected to OSS under any conditions. In healthy AVICs, OSS resulted in decreased elastin (ELN) and α-SMA (ACTA2). NOTCH LOF was associated with similar changes, but in diseased AVICs, NOTCH LOF combined with OSS was associated with increased α-SMA expression. Interestingly, AVICs showed relatively higher expression of NOTCH2 compared to NOTCH1. Biomechanical interactions between endothelial and interstitial cells involve complex NOTCH signaling that contributes to matrix homeostasis in health and disorganization in disease.

Force sensor characterization under sinusoidal excitations.

The aim in the current work is the development of a method to characterize force sensors under sinusoidal excitations using a primary standard as the source of traceability. During this work the influence factors have been studied and a method to minimise their contributions, as well as the corrections to be performed under dynamic conditions have been established. These results will allow the realization of an adequate characterization of force sensors under sinusoidal excitations, which will be essential for its further proper use under dynamic conditions. The traceability of the sensor characterization is based in the direct definition of force as mass multiplied by acceleration. To do so, the sensor is loaded with different calibrated loads and is maintained under different sinusoidal accelerations by means of a vibration shaker system that is able to generate accelerations up to 100 m/s2 with frequencies from 5 Hz up to 2400 Hz. The acceleration is measured by means of a laser vibrometer with traceability to the units of time and length. A multiple channel data acquisition system is also required to simultaneously acquire the electrical output signals of the involved instrument in real time.

192 The Induction of Homeobox Genes by Disturbed Flow Limits Inflammation at Atherosusceptible Sites

IntroductionAtherosclerosis develops at branches and bends of arteries exposed to disturbed blood flow, whereas regions exposed to uniform flow are protected. Disturbed flow generates low, oscillatory wall shear stress (WSS)...

Harmonization and characterization of different single‐use bioreactors adopting a new sparger design

In mammalian cell culture, single‐use bioreactors are widely used. Different hardware designs are available, ranging from stirred tank reactors to wave mixed and cubical shaken systems. Unlike in stainless steel systems, where standards exist, in single‐use bioreactors aeration devices are often predefined by the supplier. While ring sparger systems are the gold standard in stainless steel bioreactors, not all single‐use bioreactors are available with ring spargers. In this study, a comprehensive characterization of two stirred tank single‐use bioreactor systems (XDR™ from Xcellerex and S.U.B. from Thermo Scientific Hyclone) was performed under GMP conditions with 200/250 L and 1000 L bioreactors. Engineering facts like mass transfer rates for oxygen kLao2 and carbon dioxide kLaCO2 as well as mixing number were evaluated. To achieve improved similarity in key engineering parameters and in consequence cell culture performance, the submerse aeration device of the S.U.B. (to date only open tube and frit) was remodeled resulting in a drilled hole sparger design. Results of the characterization showed that kLao2 in the S.U.B. was enhanced from 8.5 h−1 to 11.5 h−1 at the maximum, and the kLaCO2 was very similar between both bioreactor types. Knowledge of the characterization data as well as improved oxygen transfer rate in the S.U.B. allows for an interchangeable usage of the two different single‐use bioreactors.

Abstract 266: Disturbed Flow Promotes Endothelial Cell Injury via the Induction of Developmental Genes

Introduction: Atherosclerosis is influenced by blood flow patterns which exert wall shear stress (WSS) on endothelial cells (EC). Low oscillatory WSS promotes atherosclerosis by inducing EC apoptosis and activation, whereas high unidirectional WSS is protective. We used microarray technology coupled to computational fluid dynamics to study the transcriptome of EC at regions of the porcine aorta exposed to low, oscillatory or high, unidirectional WSS. The study revealed differential expression of multiple genes that co-ordinate embryonic development. We hypothesised that this gene set includes WSS-sensitive regulators of EC survival. Methods and Results: EC were isolated from distinct anatomical regions of the porcine aorta using collagenase (n=6), and quantitative RT-PCR revealed elevated expression of developmental genes (GATA4, HAND2, TWIST1, FZD5, BMP2, SLIT2, PDGFRA, and FBN2) at the inner (low WSS) compared to the outer curvature (high WSS) (all p<0.05). Similarly, en face staining demonstrated that expression of GATA4 protein in EC was higher at the inner compared to the outer curvature of the murine aortic arch (p<0.05). Studies using cultured porcine aortic EC (n=7) or human umbilical vein EC (n=7) revealed that GATA4, HAND2, TWIST1, FZD5, BMP2, SLIT2, PDGFRA, and FBN2 were induced in HUVEC or PAEC exposed to low, oscillatory WSS for 72h using either the orbital shaking (210 rpm; +/-WSS 4 dyn/cm2) or IBIDI™ (+/-5 dyn/cm2 at 2Hz) systems (all p<0.05). The rate of caspase-3 activation was significantly higher in EC exposed to low, oscillatory WSS compared to high, unidirectional WSS (3.1% vs 0.7%; p<0.0001; n=10). Silencing of GATA4, FZD5 and BMP2 significantly reduced apoptosis in EC exposed to low, oscillatory WSS (1.2%, 0.6% and 1.6%; p<0.05). Conclusions: We conclude that WSS influences EC viability through the induction of GATA4, FZD5 and BMP2; molecules that have a well-defined role in embryonic development. Further work is required to define the molecular mechanisms that underlie the induction of apoptosis by these molecules. Our observations illuminate the molecular mechanisms that regulate the focal nature of vascular injury and atherosclerosis.

Traditional olive tree response to oil olive harvesting technologies

Traditional olive tree growing is a symbol of the Mediterranean basin agriculture. Technological development of this mostly rainfed crop has been reduced and related with employment in rural areas. In order to improve the harvesting process of this crop, this study analyses the available technologies used for fruit detachment and the introduction of a continuous harvesting system, based on a tractor-drawn canopy shaker, to work around the large canopy trees. Results showed that harvest efficiency of mass mechanical systems, such as a trunk shaker (90.5%) and canopy shaker (78.8%), was lower than that of manual harvesting and hand-held harvesting systems (98%). However, these last systems led to high debris production because they mainly extend the harvest time to increase harvest efficiency. Canopy shaker system applied the forced vibration directly to the fruit-bearing branches. This characteristic recognised that vibration transmission plays a less important role on the fruit detachment process. The continuous harvesting process around the large canopy trees in traditional olive orchards enabled relatively high harvest efficiency values to be achieved, considering the trees were not adapted to mechanical harvesting. High harvesting efficiency values were obtained mainly where the rods were in contact with the canopy. An adaptation of the tree through pruning is required to avoid large irregularities in the tree canopy, reduce fruiting inside the canopy that is unreachable by the canopy shaker rods and facilitate the penetration of the rods into the canopy in order to achieve higher harvest efficiency values.

A Model System and Chemometrics to Develop near Infrared Spectroscopic Monitoring for Chinese Hamster Ovary Cell Cultivations

Near infrared (NIR) spectroscopy is an ideal tool for biopharmaceutical process monitoring, as it can be used to generate information on key bioprocess variables rapidly online. Mammalian cell cultivation is a rapidly developing field of biopharmaceutical production where one of these key process variables is the glucose concentration. However, calibrations for the NIR-based monitoring of glucose are usually not available in the early phase of process development owing to the lack of sufficient NIR data from small-scale experiments. This article demonstrates the development of calibrations based on NIR spectroscopy (11,988.0–4297.0 cm−1) for the determination of glucose concentration in a novel shake flask model system for mammalian cell cultivation. To generate a homogeneous distribution of glucose concentration in the calibration range and to reduce the correlation between glucose and other metabolites, cultivation samples with low glucose levels were spiked with glucose, and NIR measurements were subsequently performed. Biochemical and physical variability was deliberately induced in the model system to mimic possible matrix effects typically occurring in fed-batch bioreactor cultivation samples. The specificity of the calibration model to glucose was increased by variable selection, so the spectral region between the two water peaks was used for calibration. Four mathematical pretreatments were evaluated by comparing the root-mean standard error of prediction (RMSEP) values of the models; the best preprocessing method was a novel combination of baseline offset method with the deresolve function. Our models predicted the glucose concentration in two test cultivations with an RMSEP of 3.12 mmol L−1 and 5.51 mmol L−1.

3D23 Acceleration control of 3DOF shaking table which can suppress reaction force from test models(The 12th International Conference on Motion and Vibration Control)

Vibration testing using a shaking table is a useful method for estimation of the aseismic capacity of a building. Therefore, many engineers are researching the breakdown process of buildings by vibration testing to evaluate their aseismic capacity. A vibration testing system needs to operate correctly to carry out effective examinations, but in many cases the device does not run accurately because of reaction force from the test models and cross-axis sensitivity. Especially, the multi-degree of freedom (DOF) shaking table that includes rotational DOFs is greatly influenced by the reaction force. As a result, we cannot measure the exact frequency response characteristic of the test model. Therefore, the control method of a 3 DOF electromagnetic shaking system, which includes rotational DOF, is discussed in this study. The purpose of this study is to design an acceleration control system with good tracking performance and good disturbance rejection performance. Here, we show that the test model using the proposed control system for the shaking table gives the exact frequency response. The controller is designed based on the Dual Model Matching control method, and its effectiveness is proved experimentally.

シェーキング装置の操業経験（岩国工場6マシン）

日本製紙岩国工場6マシンは1974年に稼動した。2009年以前はコート原紙を生産していたが，生産体制の再構築によりコート原紙はもとより，上質紙，産業用紙原紙など，多種多様な品種の生産を行うこととなった。しかしながら，当初生産していたコート原紙と比べ，上質紙，産業用紙原紙は顧客が異なり要求される品質も厳しく，既存設備ではその品質要求への対応が困難であった。これら背景から，顧客からの品質要求への対応と他社製品との競争力を得る事を目的として2010年12月にシェーキング装置を導入した事で，地合改善，T／Y比低減の効果を得ることができた。また，日本製紙には高速シェーキング装置の導入経験が無いことから，中・高速マシンにおけるシェーキング技術の確立と，多方面への展開，新規品種への展開を視野に入れた研究開発機としての側面も担うこととなった。本報ではシェーキング装置の設備概要と操業経験，品質変化について報告する。

A kinematic shaker system for dynamic stabilization of Rayleigh-Bénard convection

The ability to dynamically inhibit Rayleigh-Bénard convection using acceleration modulation is of interest to groups who design and study thermoacoustic machines, as the introduction of unwanted convection can have deleterious effects on the desired operation and efficiency of the device. These performance issues, caused by suspected convective instability, have been seen both in traveling wave thermoacoustic refrigerators and in cryogenic pulse tube chillers [Swift and Backhaus, J. Acoust. Soc. Am. 126, 2273 (2009)]. This presentation discusses the vibratory conditions under which a small, rectangular container of statically unstable fluid may be stabilized by vertical vibration, applying the computational methods of Carbo [Ph.D. Thesis, Penn State Univ. (2012)]. The required shaking velocities for stabilization are found to be too large for an electrodynamic shaker. As a solution, a shaker system employing a kinematic linkage to two counter-rotating flywheels, driven by a variable-speed electrical motor, produces peak-to-peak displacements of 15.24 cm to a platform mounted on two guide rails. Thus far, this shaker has produced peak speeds of up to 3.7 m/s. [Work supported by the Office of Naval Research, the ARL Walker Graduate Assistantship, and ARPA-E.]

Dynamics Simulation Analysis of Centrifuge Facility-Vibration Shaker System Virtual Mocking Based on Flexible Centrifuge Arm

In order to study the dynamic characteristics of centrifuge facility-vibration shaker system, In the establishment of centrifuge facility-vibration shaker system multi-body dynamic model based on virtual mocking technology, the virtual dynamic model of the entire centrifuge facility-vibration shaker system more close to reality is built up by the transmission of finite element of flexible centrifuge arm. This paper describes how to build the 3-D virtual prototype of centrifuge facility-vibration shaker system by using Pro/e and ADAMS software, and how to create the modal neutral file of the centrifuge arm by using ANSYS software. Considering the system as a rigid-flexible coupling system, the dynamical simulation is carried out, and the results are benefit for the further research of its kinetic behavior, dynamic and variable characteristics basis and the design of such system.

Slurry‐Based Additive Manufacturing of Ceramics

Most additive manufacturing (AM) techniques have in common that material is spread out as thin layers of a dried powder/granulate by a roller or a shaker system. These layers are mostly characterized by a low packing rate. On the other hand, appreciable densities can be reached by the use of ceramic slurries. In this context, the layer‐wise slurry deposition (LSD) has been developed. Specific features of the LSD process are reflected on the basis of already existing additive manufacturing technologies. The microstructure of laser‐sintered bodies will be discussed, and strategies for an improved microstructure during sintering will be introduced.

Fungal–bacterial synergism enhanced decolorization of reactive red 120 by response surface methodology

This study applied co-cultured fungus and bacterium shaking system with optimal medium constituents for fast and maximal decolorization of azo dye. The Aspergillus niger and Bacillus sp. were used to develop a consortium on scrub sponge, which can decolorize reactive red 120 to 90% after 24 h cultivation. Response surface methodology (RSM) was used to investigate the optimal medium composite, 0.1% malt extract and 0.7% KH2PO4, and predicted maximal decolorization achieved 92.68% for 2 h culture and experimental decolorization was 94.5% at initial 50 mg/L concentration. Residual dye was measured by UV–Vis spectrophotometer, and biodegradation metabolites were confirmed by HPLC and FTIR. We revealed a degradation pathway of reactive red 120 with release of 2-aminobenzenesulfonic acid and 3-methanesulfinylbut-3-en-2-one as final metabolite, and terminal degraded metabolites confirmed by phytotoxicity were nontoxic naturally. This study indicated the high potential of fungal–bacterial co-cultured system as an excellent technical innovation for azo dye decolorization.