Measuring vertical jump ability for leg power assessment is not necessarily a simple process. There are many jump techniques, measurement methods and equipment variations. All these can affect the results, reliability and interpretation of the test.
In its simplest form, the vertical jump test is performed as a squat jump or static jump. In this technique, the subject starts from a stationary semi-squatting position, or pauses at the lower level of the squat before jumping upwards. This removes the factor of the stretch-shortening cycle (pre-stretching of muscles) and the jump result will be smaller than other techniques described below. The difference in jump height is typically 3-6 cm without a countermovement. Example: Squat Jump
The vertical jump test is commonly performed with a counter movement, where there is bending of the knees immediately prior to the jump. The countermovement activates the stretch-shortening cycle in the muscles, resulting in greater power production in the legs. Without the use of the arms, it makes it difficult to use the traditional technique of reaching up and touching the wall. The eTID VJ protocol is a countermovement test performed with no arm swinging, though the test is performed with one hand on the hip and the other raised above the head so as to reach up the wall. The Bosco Countermovement Jump test is performed on a touch sensitive mat, so the arms can be left on the hips throughout the jump.
Using the arms during a vertical jump test is not always desirable, as it add variations due to technique and coordination, though most vertical jump tests you will see performed allow the use of the arms to help propel the body upwards, as well as a countermovement. Greater jump heights can be achieved with this method. In fact some measurement techniques are hard to conduct without the arms swinging, as they require that the arm is extended upwards to mark the wall or the vanes of the vertec can be hit. See the general vertical jump test description which gives the procedure for this method. Also see the Abalakov Jump Test, an example of the vertical jump using both arm movement and countermovement using a jump mat.
Standing vertical jump tests can also be performed off one leg to isolate that side of the body. There are also a few vertical jump test protocols that allow a run up. There is a version with one step into the jump, or with a run-up and taking off one or two feet, depending on the relevance to the sport involved. Another version used in basketball testing, the Max Touch, does not specify one or two leg takeoff, just jump as high as you can! Bosco has described a series of vertical jump tests, including those with an extra load on the shoulders, after dropping from a box and multiple repeated vertical jumps. You can read more about the Bosco Jump System.
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Right after a drilling machine and a lathe machine, a milling machine is one of the most crucial machine tools for the manufacturing industry. A major point of difference between a lathe machine and a milling machine is that the former has single-point cutting tools, but the latter has multipoint cutting tools. Basically, milling is nothing but the process of removing metals by passing the work-pieces through a rotating multi-point cutter.
The machine is able to hold multiple cutters at one point in time, and it works at a high speed for faster removal of metal. In fact, the metal removal rate for milling machines is faster than the lathe machines.
So, milling is basically of two main types: horizontal and vertical, which vary considerably in their capacities because of their orientation. Most of the machine shops work with both these types of milling equipment because each type has its own advantage. Lets take a look at the advantages of each type of milling.
The cutting tools of the horizontal milling machine will remind you more of those circular saws. The centers for horizontal milling have a number of customizations available, like rotating universal bed or multiple cutters that allow the users to cut at different angles, and not only horizontally. Think of horizontal milling as something like working with multiple machine tools during a point in time.
The best thing about horizontal milling machines is that these cut faster, and based on the milling machine in use, these can make multiple cuts at one time. At the time of facing and pocketing, the chips can be removed way quicker than lathing machines.
The horizontal milling machines are expected to last for a long time. The durable construction and size of the milling machines allow these to work with heavier and larger materials without any damage to these machines.
The motion of the vertical milling machine is a lot like a standard drilling press. As you can well understand by the name, the vertical milling machines feature a vertically spindling axis. The mechanism underlying vertical milling machines make it really useful for plunging and drilling cuts. Vertical mills are, again, categorized into two more types, namely, the turret mills and the bed mills.
In case of bed mills, the material is kept on the bed, which can be moved forward and backward horizontally, and the cutter that is attached to the spindles are guided down and up. The other type is a turret mill, which comes with a bed and a fixed spindle that moves along both horizontally and vertically for positioning the material.
The vertical milling machines are more readily available in the market because these are more widely utilized in the machine shops. For the same reason, the cost of these machines are also lesser than the horizontal milling machines.
The computerized controls for the vertical milling machines are highly user-friendly. The widespread use of these machines makes it easy to find skilled laborers for operating it. There are no special fixtures needed for the machines, as well, which make these easy to operate.
As it is clearly evident now, both these machines have several advantages that are directly related to the particular designs and materials being machined. It is important to have both these kinds of machines in the unit to make sure the company has the ability of handling all kinds of designs for their customers.
The topic of this video cutter and backlash compensation. I discuss what it is, how to deal with it and give a practical demonstration on milling a pocket using dials only, without the aid of a digital readout.
A simple chart can save a lot of time in finding the center of holes on a bolt circle. Instead of setting up a rotary table or calculating the centers with trig, just multiply the diameter of the bolt circle by the constants on the chart for the XY offsets.
Proper rpm on the lathe and mill increases tool life and productivity. This lesson discusses how to determine the proper cutting speed for various metals and how to convert that cutting speed to the correct rpm for the tool or part.
One of the most hazardous operations in the shop is drilling holes in plastic or brass, especially in the drill press. Here is a simple technique to prevent drills from grabbing when drilling soft materials.
Whether youre a green machinist or a salty shop floor veteran, this In the Loupe section is for you. Refresh on tooling geometries, learn ways to improve your machining strategy, and get caught up on up-and-coming trends in this collection of valuable posts.
The following six types of rolling mills are commonly used for rolling metals: 1. Two-High Rolling Mills 2. Three-High Rolling Mill 3. Four High Rolling Mill 4. Cluster Mill 5. Multi-High Rolling Mill 6. Universal Rolling Mill.
The two-high rolling mill consists of a two-high stand with two horizontal rolls, placed exactly one over the other. In this type of mill, one or both the rollers are adjustable. In its operation, the metal is passed between the two rollers rotating at the same speed but in opposite direction.
After each pass, the direction is reversed. The metal piece is turned through 90, which keeps the section uniform and with fine grains. Nearly 25-30 passes are required to convert an ingot into a bloom. The arrangement of two-high rolling mill is shown in Fig. 2.9 (a).
The three-high rolling mill consists of a three-high stand with three rollers, placed in a single vertical plane. The upper and bottom roller rotate in the same direction whereas the middle roller rotates in the opposite direction.
It is used for rolling of two continuous passes in a rolling sequence without reversing the drive. It has higher output rate than two-high mill. It is less expensive to manufacture. The arrangement of three-high rolling mill is shown in Fig. 2.9 (b).
The four-high rolling mill consists of four rollers, two of which are working rollers (small diameter) and the other two are backing up rollers (larger diameter). The all four rollers are arranged above one another in a vertical plane. Also, the backup rollers always have larger diameters than those of the working rollers.
If such small diameter rolls are used alone, they will bend and result in non-uniform thickness distribution along the width of the sheet. For this reason, another pair of two backup rolls are used to minimize bending and deflection of small working rolls. The arrangement of four-high rolling mill is shown in Fig. 2.9 (c).
The cluster mill consists of two working rolls and four or more backing up rolls. The number of backup or supporting rolls depends upon the amount of support required for the working (small diameter) rolls. Cluster mill is generally used in cold-rolling operation. The arrangement of cluster mill is shown in Fig. 2.9 (d).
The multi-high rolling mill consists of two small diameter working rolls, a row of intermediate driving rolls, and a raw of backup rolls. This arrangement involves a cluster of either 12 or 20 rolls, resulting in exceptional rigidity of the whole roll system.
Multi-high rolling mills are used particularly in the manufacturing of very thin sheets of thickness about 0.01 mm and width up to 2000 mm. In this case, the working rolls must have very small diameter, usually 10 mm to 30 mm.
Such small diameter working rolls make a drive practically impossible. Therefore, they are driven by friction through an intermediate row of driving rolls that are, in-turn, supported by a raw of backup rolls. The arrangement of multi-high rolling mill is shown in Fig. 2.9 (e).
The universal rolling mill consists of two vertical rolls and two horizontal rolls. The vertical rolls are idle and are arranged between the bearing chocks of the horizontal rolls in the vertical plane. Universal rolling mills are used for producing blooms from ingots and for rolling wide-flange H-section beams. The arrangement of universal rolling mill is shown in Fig. 2.9. (f).
A vertical integration is when a firm extends its operations within its supply chain. It means that a vertically integrated company will bring in previously outsourced operations in-house. The direction of vertical integration can either be upstream (backward) or downstream (forward). This can be achieved either by internally developing an extended production lineEconomies of ScaleEconomies of scale refer to the cost advantage experienced by a firm when it increases its level of output.The advantage arises due to the or by acquiring vertically.
Obtaining all the assetsTangible AssetsTangible assets are assets with a physical form and that hold value. Examples include property, plant, and equipment. Tangible assets are, resources, and expertise needed to replicate the upstream or downstream member of the supply chain.
Obtaining some stake in a supplier in the form of specialized investments or an equity stakeStockholders EquityStockholders Equity (also known as Shareholders Equity) is an account on a company's balance sheet that consists of share capital plus to obtain agency benefits by increasing the ownership interest in the outcome.
Information and product delivery experience lead times within a supply chain. In other words, there is a delay between conveying the information or supplies between the different members of a supply chain. It creates an effect that is known as the Bullwhip Effect, where information relating to the quantity demanded by the customer is amplified along the supply chain such that the manufacturer overreacts to the actual information.
By vertically integrating, greater control over production process is achieved in the sense that information flows more freely between the different supply chain members. As a result, this allows for greater flexibility in adapting to changes in demand, which improves the elasticity of supply.
In a perfectly competitive market, goods and services are traded at costs. However, most markets face some level of imperfection that allows for increased profits due to either branding, information asymmetry, market power, or other factors. As a result, the price at which a company acquires its resources is often at cost plus margin.
Through vertical integration, the company is able to reduce these input costs by the margin. In reality, the prices of input do not fall by an amount equal to the margin but within some range between the costs of production and market prices. Transfer pricingTransfer PricingTransfer pricing refers to the prices of goods and services that are exchanged between commonly controlled legal entities within an describes how two vertically integrated entities set a price for exchange while the overall entity internalizes the net benefits.
One of the primary disadvantages of vertically integrating is the increase in managerial complexity. This is because entering a new line of work requires a new set of expertise to complement the existing business. A clear result of this is the increase in divestitures to return a company to its core competency.
One instance of increased managerial complexity being a disincentive for vertical integration was when Exxon Mobil (NYSE: XOM) contemplated operating convenience stores alongside its gas stations. This is because moving into the management of retail outlets would require a new set of expertise, acquiring new suppliers, and managing the new line of business. Eventually, they did take on this forward integration but not without considering the difficulties of the integration.
Some companies are able to gain a competitive advantageCompetitive AdvantageA competitive advantage is an attribute that enables a company to outperform its competitors. It allows a company to achieve superior margins through vertical integration, whereas others instead opt to develop more efficient ways to manage their supply chain and input costs. It depends on the tradeoff of benefits and costs of integration.
SpaceX is the modern example of using vertical integration to lower the costs of its deliverable. By producing the majority of its components in-house, it is able to undercut the costs of its primary competitor, United Space Alliance. United is a joint partnership between Boeing (NYSE: BA) and Lockheed Martin (NYSE: LMT).
SpaceX enjoys several advantages over United, because of the latters dispersed supply chain where various suppliers were producing at cost plus a profit margin, resulting in an inflated cost of approximately $460 million per launch. In contrast, SpaceXs cost is $90 million per launch, which is also falling due to its reusable design.
Alternatively, McDonalds (NYSE: MCD) is known for its very dispersed supply chain due to its franchising business model. Instead of pursuing a vertical integration strategy, it uses a robust communication system between its managers and external suppliers. Part of this system is a crowdsourcing platform where various suppliers are able to share ideas and improve on individual processes and efficiency.
A financial analyst performing financial modelingWhat is Financial ModelingFinancial modeling is performed in Excel to forecast a company's financial performance. Overview of what is financial modeling, how & why to build a model. and valuation of a business should incorporate the potential synergiesTypes of SynergiesM&A synergies can occur from cost savings or revenue upside. There are various types of synergies in mergers and acquisition. This guide provides examples. A synergy is any effect that increases the value of a merged firm above the combined value of the two separate firms. Synergies may arise in M&A transactions(cost savings) that could arise from vertical integration.If the integration happens as part of a merger or acquisitionMergers Acquisitions M&A ProcessThis guide takes you through all the steps in the M&A process. Learn how mergers and acquisitions and deals are completed. In this guide, we'll outline the acquisition process from start to finish, the various types of acquirers (strategic vs. financial buys), the importance of synergies, and transaction costs, the analyst will build an M&A model in Excel and factor in the cost savings that result.
Watch this short video to quickly understand the main concepts covered in this guide, including what vertical integration is, the types of vertical integration, as well as the pros and cons of performing vertical integration.
Increased concern for environment has led to the search for more environment friendly sources of energy. Wind energy can be a viable option in this regard. Vertical axis wind turbines offer promising solution for areas away from the integrated grid systems. However, they have certain drawbacks associated with different configurations. This paper reviews various configurations of VAWT along with their merits and demerits. Moreover, design techniques employed for VAWT design have also been reviewed along with their results. It was learned that coefficient of power (CP) for various configurations is different and can be optimized with reference to Tip Speed Ratio. Latest emerging design techniques can be helpful in this optimization. Furthermore, flow field around the blade can also be investigated with the help of these design techniques for safe operation.