HYDRAULIC JUMP

A hydraulic jump is a phenomenon in the science of hydraulics which is frequently observed in open channel flow such as rivers and spillways. When liquid at high velocity discharges into a zone of lower velocity, a rather abrupt rise occurs in the liquid surface. The rapidly flowing liquid is abruptly slowed and increases in height, converting some of the flow's initial kinetic energy into an increase in potential energy, with some energy irreversibly lost through turbulence to heat. In an open channel flow, this manifests as the fast flow rapidly slowing and piling up on top of itself similar to how a shockwave forms. The phenomenon is dependent upon the initial fluid speed. If the initial speed of the fluid is below the critical speed, then no jump is possible. For initial flow speeds which are not significantly above the critical speed, the transition appears as an undulating wave. As the initial flow speed increases further, the transition becomes more abrupt, until at high enough speeds, the transition front will break and curl back upon itself. When this happens, the jump can be accompanied by violent turbulence, eddying, air entrainment, and surface undulations, or waves.
 
There are two main manifestations of hydraulic jumps and historically different terminology has been used for each. However, the mechanisms behind them are similar because they are simply variations of each other seen from different frames of reference, and so the physics and analysis techniques can be used for both types.
 
The different manifestations are:
 
The stationary hydraulic jump – rapidly flowing water transitions in a stationary jump to slowly moving water
The tidal bore – a wall or undulating wave of water moves upstream against water flowing downstream. If one considers a frame of reference which moves along with the wave front, then the wave front is stationary relative to the frame and has the same essential behavior as the stationary jump.

 Statically Determinate and indeterminate Beams

Structure is generally classified into two categories as Determinate and Indeterminate Structures or Redundant Structures for analysis of structures to find forces based on criteria discussed below. Structure is an assemblage of a number of components like slabs, beams, columns, walls, foundations and so on, which remains in equilibrium. It has to satisfy the fundamental criteria of strength, stiffness, economy, durability and compatibility, for its existence. Any structure is designed for the stress resultants of bending moment, shear force, deflection, torsional stresses, and axial stresses. If these moments, shears and stresses are evaluated at various critical sections, then based on these, the proportioning can be done. Evaluation of these stresses, moments and forces and plotting them for that structural component is known as analysis. Determination of dimensions for these components of these stresses and proportioning is known as design.

Determinate structures are analysed just by the use of basic equilibrium equations. By this analysis, the unknown reactions are found for the further determination of stresses. Redundant or indeterminate structures are not capable of being analysed by mere use of basic equilibrium equations. Along with the basic equilibrium equations, some extra conditions are required to be used like compatibility conditions of deformations etc to get the unknown reactions for drawing bending moment and shear force diagrams. Example of determinate structures are: simply supported beams, cantilever beams, single and double overhanging beams, three hinged arches, etc. Examples of indeterminate structures are: fixed beams, continuous beams, fixed arches, two hinged arches, portals, multistoried frames, etc. Special methods like strain energy method, slope deflection method, moment distribution method, column analogy method, virtual work method, matrix methods, etc are used for the analysis of redundant structures.
 
Indeterminate Structures: A structure is termed as statically indeterminate, if it can not be analysed from principles of statics alone, i.e. clip_image001. A statically indeterminate structure may be classified as:
Externally indeterminate, (example: continuous beams and frames)
Internally indeterminate, (example: trusses )
Both externally and internally indeterminate, (example: trussed beams, continuous trusses )

WASTEWATER TREATMENT prepared by Mrs Ancy

STEPS IN WASTEWATER TREATMENT

1.    SCREENING AND PUMPING
The incoming wastewater passes through screening equipment where objects such as rags, wood fragments, plastics, and grease are removed. The material removed is washed and pressed and disposed of in a landfill. The screened wastewater is then pumped to the next step: grit removal.

2.    GRIT REMOVAL
Grit settles by gravity into the bottom of the tank (in a grit hopper) while effluent exits at the top of the tank. The grit that settles into the grit hopper may be removed by a grit pump or an airlift pump. A detritus tank (or square tank degritter) is a constant-level, short-detention settling tank.

3.    PRIMARY SETTLING.
Primary settling is the process by which the velocity of the sewage is reduced below the point at which it can transport the suspended matter, so that much of this settles and can be removed as sludge.

4.    AERATION / ACTIVATED SLUDGE.
Aeration in an activated sludge process is based on pumping air into a tank, which promotes the microbial growth in the wastewater. ... After settling in a separate settling tank, bacteria forming the "activated sludge" flocks are continually recirculated back to the aeration basin to increase the rate of decomposition.
 
5.    SECONDARY SETTLING.
Secondary settling is the final step of the activated sludge-based biological wastewater treatment. Secondary settling tanks (SSTs) are therefore an essential unit of producing a clear effluent.

6.    FILTRATION
Filtration is a physical, biological, or chemical operation that separates solid matter and fluid from a mixture with a filter medium that has a complex structure through which only the fluid can pass.

 
7.    DISINFECTION
Killing, removal, or deactivation of harmful microorganisms can be referred to as disinfection. Destruction or deactivation of pathogenic microorganisms results in stopping their reproduction and growth. People may fall ill by consuming the contaminated water containing the pathogenic microorganisms.

8.    OXYGEN UPTAKE
Aerobic capacity is commonly described by the o₂max, or maximal oxygen uptake. This measurement is an indication of (1) the ability of the cardiovascular system to provide oxygen to working muscles and (2) the ability of those muscles to extract oxygen for energy generation in the form of adenosine triphosphate (ATP).

 

CONSTRUCTION EQUIPMENT

Civil engineering relies on survey equipment, earth moving equipment, heavy machinery, and other tools to make their jobs more comfortable and efficient. Without the heavy equipment they use, the structures they build and design wouldn’t be safe.  Civil engineers also use geographic information systems and various drafting tools to map out and plot specific locations. Civil construction also uses software to help them design the structures that need to be built at that location. This is in addition to the different types of survey equipment civil engineers use to measure land and water areas, which may include a sophisticated GPS system designed for these types of applications.

Principles of Management

 

Top 16 Principles of Management Prepared by Dr. Balamurugan R

 

This article throws light upon the top sixteen principles of management of an enterprise. Some of the principles are: 1. Division of Work 2. Authority and Responsibility 3. Discipline 4. Unity of Command 5. Unity of Direction 6. Subordination of individual Interest to General Interest 7. Remuneration of Personnel and Others.
 

 
 
Management Principle # 1. Division of Work:
This is nothing but the principles of specialisation needed for proper and efficient work performance in all spheres of activity, both technical and managerial.
The overall work of an enterprise are divided into several divisions. The work of each division is entrusted to a particular worker or a group of workers to perform. This improves efficiency.
 
Management Principle # 2. Authority and Responsibility:
“Authority is the right to give orders and the power to exact obedience.” Whenever a manager is allocated tasks, he should be given requisite authority so that the particular manager can exercise his own skill and initiative for performing the entrusted tasks. Delegation of authority to managers necessarily signifies that they have responsibility for the delegated tasks.
“Responsibility is the corollary of authority, it is its natural consequences and essential counterpart.” In order to discharge responsibility properly, authority must be commensurate with responsibility. If there is no parity between the two, there will be either wastage or misuse of authority.
Management Principle # 3. Discipline:
Discipline is absolutely essential for smooth running of business. Discipline must be maintained in all its levels for successful management. Fayol points out that for the maintenance of discipline, efficient and good managers are needed at the top level and there should be clear agreement between the employer and the employees. Discipline is of paramount importance for the smooth running of production.
 
Management Principle # 4. Unity of Command:
This principle makes it clear that an employee should receive orders from one superior only. One person will command one worker or each group of workers. If several commands come from different masters to the workers, the latter may be bewildered as to what is to be done or whose order should be followed.
 
Management Principle # 5. Unity of Direction:
According to this principle, direction to work must come to the workers of each department or section from one authority. In other words; each group of activity with the same objective must have one head and one plan.
Unity of direction is different from unity of command in the sense that the former is concerned with functioning of the organisation in respect of its grouping of activities or planning, while the latter is concerned with functioning of the personnel at all levels in the organisation.
 
Management Principle # 6. Subordination of individual Interest to General Interest:
This principle demands that in management the common interest is considered to be over and above the individual interest. When there is any conflict between the two, the manager should reconcile them.
 
Management Principle # 7. Remuneration of Personnel:
Remuneration of personnel is the price of services rendered by them. This principle requires that the remuneration payable to the staff must be fair and reasonable and it should bring maximum possible satisfaction for both the employees and the employers. The remuneration factor must not cause any grievance for either party.
 
Management Principle # 8. Centralisation:
In management, ‘centralisation’ means the centralised authority or leadership of an organisation and ‘decentralisation’ signifies the dispersal of such authority or leadership to different levels of an organisation. The principle of centralisation calls for that a balanced system of centralisation must be introduced to produce the best results taking into consideration the individual circumstances.
The objective to pursue is the optimum utilisation of all faculties of the personnel. So the question of centralisation and decentralisation is a matter of proportion. In small firms, there is absolute centralisation, but in large concerns, there are a series of intermediaries between the top and bottom level and, as such, decentralisation of authority is essential.
So the principle to be followed in this respect is to maintain a proper balance between the two.
 
Management Principle # 9. Scalar Chain:
It is the chain of superiors running from the highest authority to the lowest level for the purpose of communication. The highest level of the organization must be linked with its different levels by a line of direct authority. It implies that each communication going up or coming down must flow through each position in the line of authority.
 
Management Principle # 10. Order:
This principle refers to the arrangement of persons and things required in any organisation. Order is divided into material order and social order. In material order, there should be a “place for everything and everything in its place”, so that wastage of materials can be avoided.
Similarly, in social order, there should be a “place for everyone and everyone in his place” that is the placement of “right man in right job.” This kind of order demands precise knowledge of the human requirements and resources of the organisation and a constant balance between these requirements and resources.
 
Management Principle # 11. Equity:
This principle calls for the maintenance of an attitude of justice and generosity towards the working personnel and treating them equally and sympathetically. This is necessary to secure devotion and loyalty of the subordinates for good performance.
 
Management Principle # 12. Stability of Tenure of Personnel:
Stability of tenure of service is essential to get an employee accustomed to new work and succeeding in doing it perfectly and well. For this purpose, as far as possible, frequent and unnecessary labour turnover should be avoided’ because instability is both the cause and effect of bad management.
 
Management Principle # 13. Initiative:
Initiative is the power of thinking out and execution of a plan. It is one of the powerful stimulants of human endeavour. So to create zeal and energy, the managers should permit the employees to exercise as much initiative as possible.
Management Principle # 14. Team Spirit:
It means the unity of spirit or, in other words, team-spirit. This unity of spirit is the moving force which ensures maximum of co-ordinated efficiency in any undertaking. Collective effort is essential for the success of any enterprise.
So the managers should create a mentality of co-operation and team spirit among all the working personnel of the enterprise, so that they work as a team for its success. Besides these principles as enunciated by Henry Fayol, in modern management science a few more principles have been introduced.
 
Management Principle # 15. Flexibility:
Management should be flexible in nature. Its activities should be so planned, organised, directed and controlled that it can adjust with the changed time and circumstances. Market conditions are subject to constant changes. Price of commodities, tastes and fashions, demand for the products are also changing. New machinery and equipment are being found out newer varieties of products are now manufactured.
All these changes and technological advancements require supporting changes in the technique of production and business policies. Therefore, it becomes imperative that the management technique should be as flexible as possible to adjust with these changing conditions.
Management Principle # 16. Sound Organisation:
Organisation is the framework of management. For effective management of the different affairs of the business, a sound organisation is to be built up. The type of organisation depends on the nature of business, the nature of product and the technique of production.
In the cases of diversification of products and the production of standardised products in different places administrative authority is to be decentralised to a great extent. In the case of others, particularly production of a single item, centralised leadership is preferred.

 

 Prestressed concrete girders

Prestressed concrete girders are the leading choice for bridge construction across the country, and it's easy to understand why. Compared to other materials and bridge superstructures, studies show prestressed I-beam girders have the longest service life and require less maintenance.

 

The Earth's Structure

​​The earth is made up of three different layers: the crust, the mantle and the core. 

The crust

This is the outside layer of the earth and is made of solid rock, mostly basalt and granite. There are two types of crust; oceanic and continental. Oceanic crust is denser and thinner and mainly com​posed of basalt.  Continental crust is less dense, thicker, and mainly composed of granite.

The mantle

The mantle lies below the crust and is up to 2900 km thick.  It consists of hot, dense, iron and magnesium-rich solid rock. The crust and the upper part of the mantle make up the lithosphere, which is broken into plates, both large and small. To learn more about these plates see the Plate Tectonics page​. 

The core

The core is the centre of the earth and is made up of two parts: the liquid outer core and solid inner core. The outer core is made of nickel, iron and molten rock. Temperatures here can reach up to 50,000 C.

SOME FORMS OF CRUST

FOLD: 

Permanent wavelike deformation in layered rock or sediment. 

FAULT: 

A fracture in bedrock along which rocks on one side have moved relative to the other side. 

JOINT: 

A fracture on a rock without noticeable movement.