Whether injected directly in-vivo, or cultured ex-vivo on scaffolds prior to implantation, understanding the response of MSCs to physical forces is of critical importance when developing cell based therapies for cartilage repair. Our hypothesis was that intermittent dynamiccompression applied daily to MSCs in agarose culture in a chemically defined medium supplemented with TGF-β3 would enhance chondrogenesis, resulting in the formation of a more functional cartilaginous tissue. No evidence was found to support this hypothesis. Rather dynamic compressive loading was observed to inhibit chondrogenesis of MSCs in the presence of TGF-β3.
We investigate the capabilities of dynamiccompression by intense heavy ion beams to yield information about the high pressure phases of hydrogen. Employing ab initio simulations and experimental data, a new wide range equation of state for hydrogen is constructed. The results show that the melting line up to its maximum as well as the transition from molecular fluids to fully ionized plasmas can be tested with the beam parameters soon to be available. We demonstrate that x-ray scattering can distinguish between phases and dissociation states.
The aim of the fitting of the linear amplification was to restore loudness perception for medium loudness. However, the presentation levels used during the rhyme test in quiet were well below this category most of the time. This might raise the question as to whether the comparison between in- stantaneous dynamiccompression and linear amplification was fair after all, since dynamiccompression uses higher gains at lower levels. Even when comparing speech intelli- gibility at the same output level of both processing schemes, as was done here, the frequency shape of the output signals will be di ﬀ erent, and part of the speech spectrum was most likely inaudible with linear amplification for low presenta- tion levels. One could assume that the similarity of the re- sults that we observe would stem from a tradeoﬀ between in- audibility for linear amplification and distortions for instan- taneous dynamiccompression. But if audibility of these parts of the spectrum played a role, we would expect to see an ad- vantage for linear amplification over instantaneous dynamiccompression with increased level, where audibility is assured, but distortions are still present. Since we do not see such an advantage for linear amplification for high levels in the re- sults, we may assume that the audibility question for linear amplification plays only a minor role in this setup. Regard- less of the audibility question, results show that the distor- tions do not lead to a discrimination loss. However, further studies should use a linear reference response which is ad- justed to the average response of the compression system for each specific condition and level, similar to what was done post hoc in Figure 5.
This study compares the results of the locking compression plate (LCP) and the dynamiccompression plate (DCP) in the treatment of diaphyseal forearm fractures in adults and defines the indications for the use of the LCP. Forty-two patients with diaphyseal forearm fractures were retrospectively analyzed. Of those, 22 had been treated with the LCP (LCP group) and 20 had been treated with the DCP (DCP group). The AO/ASIF classification was used to classify the fractures. Patients were assessed using the Grace-Eversmann criteria and the Disabilities of the Arm and Shoulder and Hand questionnaire during the final follow-up. Mean follow-up was 21 months (range, 20- 24 months) in the LCP group and 23 months (range, 19-26 months) in the DCP group. Union was achieved in all patients. Mean time to union was 15 weeks (range, 12-25 weeks) in the LCP group and 17 weeks (range, 13-24 weeks) in the DCP group. In each group, 1 patient experienced delayed union, which required no additional surgical intervention. No significant difference was found regarding the time to union between the groups (P > .05). No significant difference existed between the 2 groups in terms of Grace-Eversmann criteria and Disabilities of the Arm and Shoulder and Hand scores (both P > .05). The results of these different fixation methods for forearm fractures in adults are similar. As such, the correct selection and application of surgical technique is more important than the type of plate used.
Fractures of the humeral shaft are relatively common, representing between 3 and 5 % of all fractures [1, 2]. Open reduction and internal fixation (ORIF) with plating is generally accepted as the best method of treatment for displaced diaphyseal fractures of the humerus in the adult, with advantages of stable fixation, direct visualization, protection of the radial nerve, and sparing of the adjacent shoulder and elbow joint from injury. Fixation techniques based on compression principles have a lower incidence of nonunion and are found to hasten rehabilitation, with less joint stiffness . Limited-contact dynamiccompression plates (LCDCPs), based on principles of dynamic com- pression and reduced bone-plate contact are used com- monly nowadays for operative fixation of fractures of the humeral shaft. Another implant, the locked compression plate (LCP), which has features of compression and point A. K. Singh ( & ) S. Garg
On a fourth specimen, a V-shaped shear fracture is visible. The presence of a V-shaped shear fracture is attributed to the diﬀerent trabeculae and cortical orienta- tion in the specimen by Van Der Westhuisen , who reported that a longitudinal cortical bone breaks with a V- shaped shear fracture across the longitudinal porosity. It was also observed that all the specimens crushed on the upper side during Quasi-Static loading. The bones tested beyond the yield point showed that the cancellous spec- imens break with a similar angle as during the dynamic tests of about 30 degrees. Bone specimens that were not loaded beyond the yield point exhibited bulge deformation (cf. Figure 9).
The response of back-supported buffer plates comprising a solid face sheet and foam core backing impacted by a column of high velocity particles (sand slug) is investigated via a lumped parameter model and coupled discrete/continuum simulations. The buffer plate is either resting (unattached) or attached to a rigid stationary foundation. The lumped parameter model is used to construct maps of the regimes of behaviour with axes of the ratio of the height of the sand slug to core thickness and the normalised core strength. Four regimes of behaviour are identified based on whether the core compression ends prior to the densification of the sand slug or vice versa. Coupled discrete/continuum simulations are also reported and compared with the lumped parameter model. While the model predicted regimes of behaviour are in excellent agreement with numerical simulations, the lumped parameter model is unable to predict the momentum transmitted to the supports as it neglects the role of elasticity in both the buffer plate and the sand slug. The numerical calculations show that the momentum transfer is minimised for intermediate values of the core strength when the so-called “soft-catch” mechanism is at play. In this regime the bounce-back of the sand slug is minimised which reduces the momentum transfer. For high values of the core strength, the response of the buffer plate resembles a rigid plate with nearly no impulse mitigation while at low values of core strength, a slap event occurs when the face sheet impinges against the foundation due to full densification of the foam core. This slap event results in a significant enhancement of the momentum transfer to the foundation. The results demonstrate that appropriately designed buffer plates have potential as impulse mitigators in landmine loading situations.
In a study conducted by Niall and Colleagues 40 in 49 cases treated by plate osteosynthesis of humeral shaft fractures and concluded that open reduction and compression plating remains the treatment of choice for non- pathological humeral shaft fractures that require operative intervention. A Study was conducted by Farragos and Schemitsch 41 on complications with locked humeral nail and to discuss the prevention and management of these complications. They concluded that advantages of locking humeral nails are many and complications diminish their usefulness. And at
Due to the computational efficiency, there are less studies of 3D simulation of cementitious composite material than 2D, and most 3D analysis only stay in static simulation. In this paper, 3D composite interface damage model is used for cementitious composite simulation, analysis the mechanical properties of dynamiccompression.
Abstract. Ceramic materials are commonly used as protective materials particularly due to their very high hardness and compressive strength. However, the microstructure of a ceramic has a great influence on its compressive strength and on its ballistic efficiency. To study the influence of microstructural parameters on the dynamic compressive behaviour of silicon carbides, isentropic compression experiments have been performed on two silicon carbide grades using a high pulsed power generator called GEPI. Contrary to plate impact experiments, the use of the GEPI device and of the lagrangian analysis allows determining the whole loading path. The two SiC grades studied present different Hugoniot elastic limit (HEL) due to their different microstructures. For these materials, the experimental technique allowed evaluating the evolution of the equivalent stress during the dynamiccompression. It has been observed that these two grades present a work hardening more or less pronounced after the HEL. The densification of the material seems to have more influence on the HEL than the grain size.
The design and assessment of concrete structures subjected to impact loads requires the knowledge of the constituent materials behaviour at higher strain-rates. Concerning con- crete, despite the e ﬀ ort and experimental work carried out so far, the data available are still relatively few. The reason of the lack of experimental data could originate from the complexity of the relevant experiments, in addition to the fact that these tests are not always directly com- parable to each other, even for the simpler compression and tension tests. Often the data have been obtained by diﬀerent experimental techniques and in dynamic testing such diﬀerences can be more marked because of the wave propagation and inertia eﬀects . For this reason it is essential that apparatuses capable of handling the wave propagation be used for the mechanical characterization of concrete at high strain-rates. It is the intention of this work to analyse the development and present some results of an innovative equipment, based on Hopkinson bar techniques, for performing dynamiccompression tests on concrete specimens of large size. The activity has been centered at the HOPLAB facility (of the Joint Research Centre at Ispra, Italy), which is basically a large-scale split Hopkinson bar. This facility is used for the study of materials and structural components to fast dynamic loads, such as those due to blasts and impacts. The problem to be eventually investigated concerns more specifically the dynamic characterization of concrete typical of dams, where very large size aggregates ( > 100 mm) may be found. Thus large specimens of representative volume have to be tested. To this end concrete specimens of maximum aggre- gate size of up to 60 mm have been produced, which in turn have required a minimum dimension of the specimens of approximately 200 mm. To investigate the compression properties and to check the influence of the hydrostatic tensor, dynamiccompression of cylindrical and confined cylindrical specimens has been planned to be conducted with specimens of 200 mm diameter and of up to 400 mm length. These are huge specimens for Hopkinson bar testing, and a particular setup of two twin bars has been
Paper deals with experimental research on the crushing of coﬀ ee beans of diﬀ erent kinds under quasi-static and dynamiccompression. The process of the crushing is described in details. It has been shown that there is variability in the crushing strength values. A relation between crushing strength and the coﬀ ee grain shape is also studied. Roasted Arabica coﬀ ee (Coﬀ ea arabica) beans were used for analyses. Arabica coﬀ ees were produced in diﬀ erent countries. All Arabica samples were submitted to a light roast. The detail analysis of the experimental data shows that there is no signiﬁ cant relation between parameters describing the fracture behaviour of the grains and grain geometry. These parameters are also independent on the grain weight. Compression of the coﬀ ee grains leads to their crushing. The fracture force is diﬀ erent for the diﬀ erent kinds of the coﬀ ee. The same is fact valid also for the strain at the fracture and for the energy absorbed during the grain crushing. Dynamic loading leads to the increase in the fracture force of coﬀ ee grains in comparison with the quasi static loading. coﬀ ee beans, compression loading, strength, impact loading
In Fig. 2 the incident, reflected and transmitted pulses measured on input and output bars in a dynamiccompression test of UHPC specimen are shown. It can be observed as at high strain rate the specimen failure is reached just in the first cycle of loading. The time necessary to bring the specimen at failure in compression is about 100 µs.
SCP is a special type of dynamic replacement which can be used for both clayey and sandy ground. The method was originated in Japan and has been widely used in Japan and other Asian countries. The method deserves special mentioning as the construction processes involved in sand compaction piles can be different from that for vibro compaction or stone columns. In forming sand compaction piles, sand is fed into the ground through a casing pipe and is compacted by vibration, dynamic impact or static excitation to form columns. Sand compaction piles can be used for the treatment of both sandy and clayey ground. This is different from vibro compaction. The main purposes of using SCPs for sandy ground are to prevent liquefaction and reduce settlement
The proposed 𝑝𝑜𝑙𝑦 − 𝐷𝑊𝑇 architecture was evaluated for different test images for the image reconstruction quality studies. The image reconstruction was achieved by forward and inverse 𝑝𝑜𝑙𝑦 − 𝐷𝑊𝑇 architectures implemented in the same hardware. Results of the test are compiled in Table 3. The 𝑝𝑜𝑙𝑦 − 𝐷𝑊𝑇 design achieves a good 𝑃𝑆𝑁𝑅 value for the test images in the range of 48 𝑑𝐵 for 𝐿𝑒 − 𝐺𝑎𝑙𝑙 5/3 filter. As expected, because the 𝐷𝑎𝑢𝑏𝑒𝑐𝑖𝑒𝑠 9/7 filter gives a lossy compression, the𝑃𝑆𝑁𝑅 value for the same test cases was poorer by a few dB. The results obtained are in correlation to the existing findings published in .
ABSTRACT : Image enhancement is carried out to improve some characteristic of an image to make it visually better one. This paper introduce a method for improving the dark region in digital images.It consist of two independent processes: luminance enhancement and contrast enhancement. The luminance enhancement, also regarded as a process of dynamic range compression, is essentially an intensity transformation based on a specifically designed nonlinear transfer function .The V channel is enhanced in two steps.First the V component image is divided into smaller overlapping blocks and for each pixel inside the block the luminance enhancement is carried out using nonlinear transfer function.then the contrast enhancement depending upon the central pixel value and its neighborhood pixel value. Finally enhanced V component image are converted back to RGB image. For measuring the visual quality of enhanced images reduced reference(RR) metrics are proposed. Experimental result showed that the proposed RR metrics work well for measuring the visual quality of spatially enhanced images.
With the rapidly growing amounts of facts produced global, networked and multi-consumer storage systems have become very famous. However, worries over information safety still prevent many customers from migrating facts to far-flung garage. The conventional solution is to encrypt the information earlier than it leaves the owner’s premises. While sound from a safety angle, this method prevents the garage issuer from effectively making use of storage efficiency capabilities, which includes compression and deduplication, which could permit best utilization of the resources and consequently lower carrier fee. Client-aspect data deduplication particularly ensures that more than one uploads of the equal content handiest devour community bandwidth and garage area of a unmarried upload. A number of cloud backup providers as well as various cloud services actively use deduplication. Unfortunately, encrypted facts are pseudorandom and consequently cannot be deduplicated: therefore, cutting-edge schemes need to completely sacrifice both security and garage performance. In this paper, we present schemes that permit a greater quality-grained change-off in records chunk similarity. The instinct is that outsourced records may additionally require exceptional degrees of safety, relying on how popular it is miles content material shared through many users. Various deduplication schemes are analyze and provide experimental outcomes that suggest proposed cozy facts bite similarity provide improved effects in real time cloud environments.
3) Dictionary Based Compression: To further reduce the size, we take the advantage of the temporal locality. Temporal locality exists since the basic blocks repeat frequently, which implies the branch and target addresses after Phase 1 repeat frequently. The idea is to map the data to a table keeping frequently appeared data, and record the table index instead of the data to reduce size. Fig.6 shows the hardware architecture. The dictionary keeps the frequently appeared branch/target addresses. To keep the hardware cost reasonable, the proposed dictionary is implemented with a CAM based FIFO. When it is full, the new address will replace the address at the first entry of FIFO. For each input datum , the comparator compares the datum with the data in the dictionary . If the datum is not in the table ( , the datum is written into the table and also recorded in a trace. Otherwise ( , the index of the hit table entry is recorded instead of the datum. The hit index can be further compressed. As we know, a basic block is composed by a target address and a branch address, and the branch instruction address appears right after target instruction address. By the fact that basic blocks repeat frequently, if the target address is hit at the table entry i, the branch address will hit at the table entry + , since these entries are stored in the dictionary in a FIFO way.
The diagram (Fig. 5) illustrates the obtained results for calculating dependence of dynamic amplification factor for beams with and without longitudinal compression in conventional elastic stage. The data are given for a certain limit state 1 а and rigid support depending on the product of first mode natural frequencies (ω 1 ) and time of dynamic load application (θ).