阅读说明：本技术 一种用于城市大气污染治理的方法 (Method for treating urban atmospheric pollution ) 是由 韩冰 汪为忠 韩晓春 席颖 杨家奎 于 2019-08-01 设计创作，主要内容包括：本发明公开了一种用于城市大气污染治理的方法,包括以下几个步骤：S1、确定城市污染源；S2、在城市污染源处设立隔离罩,将污染源囊括在隔离罩；S3、建立废气处理中心,将隔离罩内污染源产生的废气通过抽气管到抽进废气处理中心内,进行气体净化工作后,再通过出气管,将净化后的空气输入隔离罩内；S4、设置隔离罩绿化带：在隔离罩的外部表面铺设绿化植被,绿化植被在隔离罩外部表面的覆盖率不低于90％；S5、建立绿化带养护设备：根据植被生长对水份的需求量,定期对隔离罩绿化带进行灌溉作业,确保种植的绿化植被快速生长,同时对出现死亡的植被进行补种作业；再根据绿化带生长需肥量以及病虫害治理药水量对绿化带定期进行施肥和病虫防治。(The invention discloses a method for treating urban atmospheric pollution, which comprises the following steps: s1, determining an urban pollution source; s2, setting an isolation cover at the urban pollution source, and enclosing the pollution source in the isolation cover; s3, establishing a waste gas treatment center, pumping waste gas generated by a pollution source in the isolation cover into the waste gas treatment center through the exhaust pipe, purifying the gas, and inputting the purified air into the isolation cover through the air outlet pipe; s4, setting a green belt of the isolation cover: paving greening vegetation on the outer surface of the isolation cover, wherein the coverage rate of the greening vegetation on the outer surface of the isolation cover is not lower than 90%; s5, establishing green belt maintenance equipment: according to the water demand for vegetation growth, regularly irrigating the green belts of the isolation hoods, ensuring the rapid growth of the planted greening vegetation, and simultaneously performing reseeding operation on the vegetation which is dead; and then periodically fertilizing and preventing diseases and pests on the green belt according to the growth fertilizer requirement of the green belt and the amount of the pesticide for controlling the diseases and pests.)

1. the method for treating the urban atmospheric pollution is characterized by comprising the following steps of:

s1, determining urban pollution sources: the system comprises an automobile tail gas emission point of an urban garage, a garbage stacking point, an industrial area waste gas emission point and a station waste gas emission point;

s2, setting an isolation cover: at the urban pollution source determined in the step S1, setting an isolation cover to enclose the pollution source in the isolation cover;

S3, establishing an exhaust gas treatment center: establishing a waste gas treatment center outside the isolation cover established in the step S2, pumping waste gas generated by the pollution source in the isolation cover into the waste gas treatment center through an exhaust pipe, purifying the gas, and inputting the purified air into the isolation cover through an air outlet pipe;

s4, setting a green belt of the isolation cover: paving greening vegetation on the outer surface of the isolation cover, wherein the coverage rate of the greening vegetation on the outer surface of the isolation cover is not lower than 90%;

s5, establishing green belt maintenance equipment: periodically irrigating the green belt of the isolation hood according to rainfall of the natural environment, water evaporation amount of a restoration operation surface and water demand of a vegetation growth period, ensuring the rapid growth of planted greening vegetation, and simultaneously performing reseeding operation on the vegetation which is dead; and then periodically fertilizing and preventing diseases and pests on the green belt according to the growth fertilizer requirement of the green belt and the amount of the pesticide for controlling the diseases and pests.

2. the method as claimed in claim 1, wherein the shielding case in step S2 is a house-like structure enclosing a source of the urban atmospheric pollution, the house-like structure is a net-like structure constructed by a plurality of steel bars, the net-like surface of the shielding case is provided with a net, the metal nets are laid on the surface of the shielding case from top to bottom, adjacent metal nets are connected in a butt joint manner, the lap joint distance is not less than 10 cm, and the metal nets are fixed by fine iron wires.

3. The method for urban atmospheric pollution abatement according to claim 1, wherein, the waste gas treatment center in the step S3 comprises an exhaust tube, an exhaust fan, an exhaust pipe, an exhaust fan, a waste gas purification system, a control mechanism, a driving mechanism and a power supply mechanism, wherein the power supply mechanism provides power for the control mechanism, the driving mechanism, the waste gas purification system, the exhaust fan and the exhaust fan, the control mechanism controls the exhaust fan, the driving mechanism and the exhaust fan to work, the exhaust fan extracts waste gas in an atmosphere pollution source in the isolation cover through the exhaust tube, the driving mechanism reflects the treatment mechanism in the waste gas purification system to implement waste gas treatment work, and the waste gas purification system purifies the waste gas, the gas outlet fan conveys the purified gas into the isolation hood through the gas outlet pipe to form a gas circulation treatment pipeline.

4. the method for treating urban atmospheric pollution according to claim 1, wherein the preparation method of the isolation cover green belt comprises the following steps: and spraying the plant cushion matrix onto the metal net on the surface of the isolation cover by using a spraying device until the spraying thickness of the plant cushion matrix on the metal net is 12-17 cm.

5. The method as claimed in claim 1, wherein the green belt maintenance equipment comprises a spray pipe, a water pump, a water pipe, a water supply tank, a liquid medicine tank and a PLC controller, the spray pipe, the water pump, the water pipe, the water supply tank, the liquid medicine tank and the PLC controller are arranged around the green belt of the isolation hood, the PLC controller controls the water pump, and the water pump drives the water pipe to convey water in the water supply tank or the liquid medicine tank into the spray pipe to water or treat the green belt with medicines.

6. the method for urban atmospheric pollution abatement according to claim 4, wherein the plant mat substrate comprises a substrate bottom layer and a substrate surface layer, wherein the substrate bottom layer is made from the following raw materials: the soil fertilizer comprises, by weight, 40-50 parts of planting soil, 20-25 parts of nutrient soil, 2-4 parts of plant gum, 1-2 parts of a water-retaining agent, 5-10 parts of straw fiber, 5-10 parts of grain shell powder, 5-10 parts of sawdust, 0.2-0.4 part of trace element, 5-8 parts of organic fertilizer, 2-3 parts of slow release fertilizer, 4-6 parts of loam-like soil matrix agent and a proper amount of water; the surface layer of the matrix is prepared from the following raw materials: the soil-planting fertilizer comprises, by weight, 40-50 parts of planting soil, 20-25 parts of nutrient soil, 2-4 parts of plant glue, 1-2 parts of a water-retaining agent, 5-10 parts of straw fibers, 5-10 parts of grain shell powder, 5-10 parts of sawdust, 0.2-0.4 part of trace elements, 5-8 parts of an organic fertilizer, 2-3 parts of a slow-release fertilizer, 4-6 parts of a loam-like soil matrix agent, a proper amount of water and 3-5 parts of vegetation seeds.

7. The method for urban atmospheric pollution abatement according to claim 6, wherein the preparation method of the substrate bottom layer comprises the following steps:

s1, preparing raw materials: 40-50 parts of planting soil, 20-25 parts of nutrient soil, 2-4 parts of plant gum, 1-2 parts of water-retaining agent, 5-10 parts of straw fiber, 5-10 parts of grain shell powder, 5-10 parts of sawdust, 0.2-0.4 part of trace element, 5-8 parts of organic fertilizer, 2-3 parts of slow release fertilizer, 4-6 parts of loam-like matrix agent and a proper amount of water;

s2, uniformly stirring the planting soil, the nutrient soil, the plant gum, the water-retaining agent, the straw fiber, the cereal shell powder, the wood chips, the trace elements, the organic fertilizer, the slow-release fertilizer and the loam-like soil matrix agent in parts by weight to obtain a mixed material;

s3, adding a proper amount of water into the mixture obtained in the step S2, and stirring again until the water and the mixture are uniformly stirred to form a matrix mixture;

s4, performing viscosity test on the substrate mixture in the step S3 until the substrate mixture is in a state that the consistency can be bonded on the metal mesh surface and does not flow, and spraying the substrate mixture onto the metal mesh surface of the isolation cover by adopting a spraying device, wherein the spraying thickness is 7-10 cm.

8. The method for urban atmospheric pollution abatement according to claim 6, wherein the preparation method of the substrate surface layer comprises the following steps:

S1, preparing raw materials: 40-50 parts of planting soil, 20-25 parts of nutrient soil, 2-4 parts of plant gum, 1-2 parts of water-retaining agent, 5-10 parts of straw fiber, 5-10 parts of grain shell powder, 5-10 parts of sawdust, 0.2-0.4 part of trace element, 5-8 parts of organic fertilizer, 2-3 parts of slow release fertilizer, 4-6 parts of loam-like soil matrix agent, 3-5 parts of vegetation seeds and a proper amount of water;

S2, uniformly stirring the planting soil, the nutrient soil, the plant gum, the water-retaining agent, the straw fiber, the cereal shell powder, the wood chips, the trace elements, the organic fertilizer, the slow-release fertilizer, the loam-like matrix agent and the vegetation seeds in parts by weight to obtain a mixed material;

S3, adding a proper amount of water into the mixture obtained in the step S2, and stirring again until the water and the mixture are uniformly stirred to form a matrix mixture;

s4, performing viscosity test on the substrate mixture in the step S3 until the substrate mixture is in a state that the consistency can be bonded on the metal mesh surface and does not flow, and spraying the substrate mixture onto the upper surface of the substrate bottom layer by adopting a spraying device, wherein the spraying thickness is 5-7 cm.

Technical Field

The invention relates to the technical field of environmental improvement methods, in particular to a method for treating urban atmospheric pollution.

background

along with the reasons of industrial and agricultural development, natural environment deterioration and the like, a plurality of enterprises discharge pollution to the atmosphere to cause pollution to the surrounding environment, particularly, the air quality is worse and worse due to limited greening area and poor purification capacity in cities, in recent years, the haze pollution is also worse and worse, no quick and effective treatment method is available at present, and the long-term air pollution causes serious harm to the life and the personal health of residents in densely populated areas. Therefore, the invention provides a method for treating urban atmospheric pollution, which can solve the problems.

Disclosure of Invention

the invention aims to provide a method for urban atmospheric pollution treatment, which aims to solve the problems in the background technology.

in order to achieve the purpose, the invention provides the following technical scheme: a method for urban atmospheric pollution abatement comprises the following steps:

S1, determining urban pollution sources: the system comprises an automobile tail gas emission point of an urban garage, a garbage stacking point, an industrial area waste gas emission point and a station waste gas emission point;

s2, setting an isolation cover: at the urban pollution source determined in the step S1, setting an isolation cover to enclose the pollution source in the isolation cover;

s3, establishing an exhaust gas treatment center: establishing a waste gas treatment center outside the isolation cover established in the step S2, pumping waste gas generated by the pollution source in the isolation cover into the waste gas treatment center through an exhaust pipe, purifying the gas, and inputting the purified air into the isolation cover through an air outlet pipe;

S4, setting a green belt of the isolation cover: paving greening vegetation on the outer surface of the isolation cover, wherein the coverage rate of the greening vegetation on the outer surface of the isolation cover is not lower than 90%;

S5, establishing green belt maintenance equipment: periodically irrigating the green belt of the isolation hood according to rainfall of the natural environment, water evaporation amount of a restoration operation surface and water demand of a vegetation growth period, ensuring the rapid growth of planted greening vegetation, and simultaneously performing reseeding operation on the vegetation which is dead; and then periodically fertilizing and preventing diseases and pests on the green belt according to the growth fertilizer requirement of the green belt and the amount of the pesticide for controlling the diseases and pests.

As a preferred technical scheme of the present invention, the isolation hood described in step S2 is a house-like structure including an urban atmospheric pollution source, the house-like structure is a net built by a plurality of steel bars, the net hanging construction is performed on the net surface on the surface of the isolation hood, the metal nets are tiled on the surface of the isolation hood from top to bottom, the adjacent metal nets are connected in a butt joint manner, the lap joint distance is not less than 10 cm, and the metal nets are fixed by fine iron wires.

as a preferred technical solution of the present invention, the waste gas treatment center in step S3 includes an exhaust pipe, an exhaust fan, a waste gas purification system, a control mechanism, a driving mechanism, and a power mechanism, where the power mechanism provides power for the control mechanism, the driving mechanism, the waste gas purification system, the exhaust fan and the exhaust fan, the control mechanism controls the operation of the exhaust fan, the driving mechanism, and the exhaust fan, the exhaust fan extracts waste gas in an atmosphere pollution source in the isolation hood through the exhaust pipe, the driving mechanism reflects the treatment mechanism in the waste gas purification system to perform waste gas treatment, and after the waste gas purification system purifies the waste gas, the exhaust fan conveys the purified gas into the isolation hood through the exhaust pipe to form a gas circulation treatment pipeline.

as a preferred technical scheme of the invention, the preparation method of the isolation cover green belt comprises the following steps: and spraying the plant cushion matrix onto the metal net on the surface of the isolation cover by using a spraying device until the spraying thickness of the plant cushion matrix on the metal net is 12-17 cm.

As a preferred technical scheme, the green belt maintenance equipment comprises an atomizing pipe, a water pump, a water pipe, a water supply tank, a liquid medicine tank and a PLC (programmable logic controller) which are arranged around a green belt of the isolation hood, wherein the PLC controls the water pump, and the water pump drives the water pipe to input water in the water supply tank or the liquid medicine tank into the atomizing pipe so as to irrigate or treat the green belt with medicines.

As a preferred technical scheme of the invention, the plant pad substrate comprises a substrate bottom layer and a substrate surface layer, wherein the substrate bottom layer is prepared from the following raw materials: the soil fertilizer comprises, by weight, 40-50 parts of planting soil, 20-25 parts of nutrient soil, 2-4 parts of plant gum, 1-2 parts of a water-retaining agent, 5-10 parts of straw fiber, 5-10 parts of grain shell powder, 5-10 parts of sawdust, 0.2-0.4 part of trace element, 5-8 parts of organic fertilizer, 2-3 parts of slow release fertilizer, 4-6 parts of loam-like soil matrix agent and a proper amount of water; the surface layer of the matrix is prepared from the following raw materials: the soil-planting fertilizer comprises, by weight, 40-50 parts of planting soil, 20-25 parts of nutrient soil, 2-4 parts of plant glue, 1-2 parts of a water-retaining agent, 5-10 parts of straw fibers, 5-10 parts of grain shell powder, 5-10 parts of sawdust, 0.2-0.4 part of trace elements, 5-8 parts of an organic fertilizer, 2-3 parts of a slow-release fertilizer, 4-6 parts of a loam-like soil matrix agent, a proper amount of water and 3-5 parts of vegetation seeds.

as a preferred technical solution of the present invention, the preparation method of the substrate bottom layer comprises the following steps:

As a preferred technical solution of the present invention, the preparation method of the substrate bottom layer comprises the following steps:

S1, preparing raw materials: 40-50 parts of planting soil, 20-25 parts of nutrient soil, 2-4 parts of plant gum, 1-2 parts of water-retaining agent, 5-10 parts of straw fiber, 5-10 parts of grain shell powder, 5-10 parts of sawdust, 0.2-0.4 part of trace element, 5-8 parts of organic fertilizer, 2-3 parts of slow release fertilizer, 4-6 parts of loam-like matrix agent and a proper amount of water;

S2, uniformly stirring the planting soil, the nutrient soil, the plant gum, the water-retaining agent, the straw fiber, the cereal shell powder, the wood chips, the trace elements, the organic fertilizer, the slow-release fertilizer and the loam-like soil matrix agent in parts by weight to obtain a mixed material;

S3, adding a proper amount of water into the mixture obtained in the step S2, and stirring again until the water and the mixture are uniformly stirred to form a matrix mixture;

S4, performing viscosity test on the substrate mixture in the step S3 until the substrate mixture is in a state that the consistency can be bonded on the metal mesh surface and does not flow, and spraying the substrate mixture onto the metal mesh surface of the isolation cover by adopting a spraying device, wherein the spraying thickness is 7-10 cm.

As a preferred technical solution of the present invention, the preparation method of the substrate surface layer comprises the following steps:

s1, preparing raw materials: 40-50 parts of planting soil, 20-25 parts of nutrient soil, 2-4 parts of plant gum, 1-2 parts of water-retaining agent, 5-10 parts of straw fiber, 5-10 parts of grain shell powder, 5-10 parts of sawdust, 0.2-0.4 part of trace element, 5-8 parts of organic fertilizer, 2-3 parts of slow release fertilizer, 4-6 parts of loam-like soil matrix agent, 3-5 parts of vegetation seeds and a proper amount of water;

S2, uniformly stirring the planting soil, the nutrient soil, the plant gum, the water-retaining agent, the straw fiber, the cereal shell powder, the wood chips, the trace elements, the organic fertilizer, the slow-release fertilizer, the loam-like matrix agent and the vegetation seeds in parts by weight to obtain a mixed material;

s3, adding a proper amount of water into the mixture obtained in the step S2, and stirring again until the water and the mixture are uniformly stirred to form a matrix mixture;

s4, performing viscosity test on the substrate mixture in the step S3 until the substrate mixture is in a state that the consistency can be bonded on the metal mesh surface and does not flow, and spraying the substrate mixture onto the upper surface of the substrate bottom layer by adopting a spraying device, wherein the spraying thickness is 5-7 cm.

Compared with the prior art, the invention has the beneficial effects that: the invention has high air purification efficiency by arranging the isolation cover, the isolation cover green belt and the waste gas treatment center, can effectively treat and filter the urban air pollution source, can absorb and fix harmful substances by organisms, can effectively meet the requirement of continuously and stably fixing the pollutants while playing a role of increasing the urban greening effect, and can prevent the pollutants from causing secondary pollution, thereby achieving the purpose of improving the air quality.

Detailed Description

the technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention

the invention provides a technical scheme that: a method for urban atmospheric pollution abatement comprises the following steps:

s1, determining urban pollution sources: the system comprises an automobile tail gas emission point of an urban garage, a garbage stacking point, an industrial area waste gas emission point and a station waste gas emission point;

s2, setting an isolation cover: at the urban pollution source determined in the step S1, setting an isolation cover to enclose the pollution source in the isolation cover;

S3, establishing an exhaust gas treatment center: establishing a waste gas treatment center outside the isolation cover established in the step S2, pumping waste gas generated by the pollution source in the isolation cover into the waste gas treatment center through an exhaust pipe, purifying the gas, and inputting the purified air into the isolation cover through an air outlet pipe;

s4, setting a green belt of the isolation cover: paving greening vegetation on the outer surface of the isolation cover, wherein the coverage rate of the greening vegetation on the outer surface of the isolation cover is not lower than 90%;

s5, establishing green belt maintenance equipment: periodically irrigating the green belt of the isolation hood according to rainfall of the natural environment, water evaporation amount of a restoration operation surface and water demand of a vegetation growth period, ensuring the rapid growth of planted greening vegetation, and simultaneously performing reseeding operation on the vegetation which is dead; and then periodically fertilizing and preventing diseases and pests on the green belt according to the growth fertilizer requirement of the green belt and the amount of the pesticide for controlling the diseases and pests.

Further, the isolation hood described in step S2 is a house-like structure including an urban atmospheric pollution source, the house-like structure is a net-like structure built by a plurality of steel bars, net hanging construction is performed on the net-like surface of the isolation hood surface, metal nets are tiled on the surface of the isolation hood from top to bottom, a butt joint mode is adopted between adjacent metal nets, the lap joint distance is not less than 10 cm, and the metal nets are fixed by thin iron wires.

further, the waste gas treatment center in step S3 includes the exhaust tube, the exhaust fan, the outlet duct, the outlet fan, the waste gas purification system, a control mechanism, a driving mechanism and a power supply mechanism, the power supply mechanism provides power for the control mechanism, the driving mechanism, the waste gas purification system, the exhaust fan and the outlet fan, the control mechanism controls the exhaust fan, the driving mechanism and the outlet fan to work, the exhaust fan extracts waste gas in the atmosphere pollution source in the isolation hood through the exhaust tube, the driving mechanism reflects the treatment mechanism in the waste gas purification system to implement waste gas treatment, after the waste gas purification system performs the waste gas purification treatment, the outlet fan conveys the gas after the purification treatment into the isolation hood through the outlet duct, and a gas circulation treatment pipeline is formed.

further, the preparation method of the isolation cover green belt comprises the following steps: and spraying the plant cushion matrix onto the metal net on the surface of the isolation cover by using a spraying device until the spraying thickness of the plant cushion matrix on the metal net is 12-17 cm.

further, greenbelt maintenance equipment includes spray pipe, water pump, water pipe, the pond that supplies water, liquid medicine pond and the PLC controller that sets up around the cage greenbelt, the water pump is controlled to the PLC controller, and the water pump orders about the water pipe will supply water the pond or during the water input spray pipe in the liquid medicine pond, waters or the medicine is administered the greenbelt.

further, the plant pad substrate comprises a substrate bottom layer and a substrate surface layer, wherein the substrate bottom layer is prepared from the following raw materials: the soil fertilizer comprises, by weight, 40-50 parts of planting soil, 20-25 parts of nutrient soil, 2-4 parts of plant gum, 1-2 parts of a water-retaining agent, 5-10 parts of straw fiber, 5-10 parts of grain shell powder, 5-10 parts of sawdust, 0.2-0.4 part of trace element, 5-8 parts of organic fertilizer, 2-3 parts of slow release fertilizer, 4-6 parts of loam-like soil matrix agent and a proper amount of water; the surface layer of the matrix is prepared from the following raw materials: the soil-planting fertilizer comprises, by weight, 40-50 parts of planting soil, 20-25 parts of nutrient soil, 2-4 parts of plant glue, 1-2 parts of a water-retaining agent, 5-10 parts of straw fibers, 5-10 parts of grain shell powder, 5-10 parts of sawdust, 0.2-0.4 part of trace elements, 5-8 parts of an organic fertilizer, 2-3 parts of a slow-release fertilizer, 4-6 parts of a loam-like soil matrix agent, a proper amount of water and 3-5 parts of vegetation seeds.

Further, the preparation method of the substrate bottom layer comprises the following steps:

further, the preparation method of the substrate bottom layer comprises the following steps:

s1, preparing raw materials: 40-50 parts of planting soil, 20-25 parts of nutrient soil, 2-4 parts of plant gum, 1-2 parts of water-retaining agent, 5-10 parts of straw fiber, 5-10 parts of grain shell powder, 5-10 parts of sawdust, 0.2-0.4 part of trace element, 5-8 parts of organic fertilizer, 2-3 parts of slow release fertilizer, 4-6 parts of loam-like matrix agent and a proper amount of water;

s2, uniformly stirring the planting soil, the nutrient soil, the plant gum, the water-retaining agent, the straw fiber, the cereal shell powder, the wood chips, the trace elements, the organic fertilizer, the slow-release fertilizer and the loam-like soil matrix agent in parts by weight to obtain a mixed material;

S3, adding a proper amount of water into the mixture obtained in the step S2, and stirring again until the water and the mixture are uniformly stirred to form a matrix mixture;

S4, performing viscosity test on the substrate mixture in the step S3 until the substrate mixture is in a state that the consistency can be bonded on the metal mesh surface and does not flow, and spraying the substrate mixture onto the metal mesh surface of the isolation cover by adopting a spraying device, wherein the spraying thickness is 7-10 cm.

Further, the preparation method of the matrix surface layer comprises the following steps:

s1, preparing raw materials: 40-50 parts of planting soil, 20-25 parts of nutrient soil, 2-4 parts of plant gum, 1-2 parts of water-retaining agent, 5-10 parts of straw fiber, 5-10 parts of grain shell powder, 5-10 parts of sawdust, 0.2-0.4 part of trace element, 5-8 parts of organic fertilizer, 2-3 parts of slow release fertilizer, 4-6 parts of loam-like soil matrix agent, 3-5 parts of vegetation seeds and a proper amount of water;

S2, uniformly stirring the planting soil, the nutrient soil, the plant gum, the water-retaining agent, the straw fiber, the cereal shell powder, the wood chips, the trace elements, the organic fertilizer, the slow-release fertilizer, the loam-like matrix agent and the vegetation seeds in parts by weight to obtain a mixed material;

s3, adding a proper amount of water into the mixture obtained in the step S2, and stirring again until the water and the mixture are uniformly stirred to form a matrix mixture;

S4, performing viscosity test on the substrate mixture in the step S3 until the substrate mixture is in a state that the consistency can be bonded on the metal mesh surface and does not flow, and spraying the substrate mixture onto the upper surface of the substrate bottom layer by adopting a spraying device, wherein the spraying thickness is 5-7 cm.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.