Abstract: A heating sensor capable of generating heat and measuring its own temperature is placed in a fluid and a thermometric sensor is placed in the fluid and inside a temperature boundary layer formed around the heating sensor upon heat generation therefrom. A temperature of the heating sensor and a temperature of the fluid are measured. A relationship between thermal conductivity of the fluid and a differential value between the temperature of the heating sensor and the temperature of the fluid is used to determine the thermal conductivity of the fluid. Then, the heating value of the heating sensor is adjustably increased so that the thermometric sensor is positioned outside the temperature boundary layer. A temperature of the heating sensor and the temperature of the fluid are measured. The relationship between kinematic viscosity of the fluid and a differential value between the temperature of the heating sensor and the temperature of the fluid is used to determine the kinematic viscosity of the fluid.

Abstract: A heating sensor is disposed within a pipe with a clearance between an inner wall of the pipe and an outer surface of the heating sensor such that a measurement of thermal conductivity is free from any influence of a convective heat transfer. Temperatures of the fluid and the heating sensor are measured and a differential temperature therebetween in steady state heating is determined. A correlation is established between the differential temperature and a thermal conductivity of the fluid and is utilized to obtain the thermal conductivity of this fluid.

Abstract: There is provided a circulating line branched from a solution or suspension tank and returning again to this tank through a pump (15) used to control the flow velocity at a constant level. A fluid temperature is measured by a sensor (16) in said tank or said circulating line (14) while a temperature of a heating sensor (17) employing so-called electrically heating method and placed in said circulating line is measured. Concentration of a given subject in solution or suspension is determined based on a temperature of the heating sensor or a difference between a temperature of the heating sensor and a temperature of the fluid.

Abstract: In a subject fluid, there is placed an apparatus for measuring a change in state of the fluid, said apparatus having a tubular body which, in turn, contains therein at least one heating sensor employing so-called hot wire method. A quantity of the fluid is introduced into the tubular body and a temperature of the heating sensor is measured by the heating sensor itself as the quantity of the fluid having been introduced into the tubular body is maintained in a state of laminar flow or a static state. The laminar flow is generated by fluid impeller means such as impeller vane, screw-type vane or propeller vane assembly or uniaxial eccentric pump. The static state is maintained y providing gateway means for passage of the fluid into or out from the tubular body and closing such gateway means. A temperature of the fluid having been introduced into the tubular body and maintained in said laminar or static state is measured and discharged out from the tubular body upon completion of said temperature measurements.

Abstract: Two lead wires for each, connected to opposite ends of a heat generating element are secured to a holder. These lead wires form four-point-terminals at their other ends and thereby a disposable sensor is provided. A current source and a voltmeter are connected to the terminal and changes in various properties of fluid are determined on the basis of a value of current supplied from the current source and a value of voltage measured by the voltmeter.

Abstract: The temperature of one or several sensors which are electrically heated or cooled to a temperature substantially different from a stagnant or running fluid surrounding the said sensor or sensors by applying an electric current to the said sensor or sensors, and the temperature of the said fluid are measured simultaneously to calculate the temperature difference between the said sensor or sensors and the said fluid at an equilibrium state of heat transfer at the surface of the said sensor or sensors, thereby measuring a change in state of the said fluid collectively on an in-line processing basis without disturbing the said fluid; a change in this state results in a change in heat transfer coefficient at the surface of the said sensor or sensors, the coefficient being collectively correlated with the viscosity, density, specific heat, thermal conductivity, thermal diffusivity, coefficient of volumetric expansion, flow speed or flow direction of the said fluid at a given temperature.

Abstract: A method for measuring a heat transfer coefficient between a heat transfer element and a fluid comprising a measurement of a calorific value by placing the heat transfer element into the fluid and charing the heat transfer element with electricity. A calorific value of a particular surface of the heat transfer element is the true calorific value of the entire heat transfer element, since the particular surface of the heat transfer element is thermally insulated from a residual surface of the heat transfer element so as to prevent a heat transfer of the residual surface of the heat transfer element.

Abstract: A heat-generating element and a fluid temperature measuring element are immersed in a molten or gelled fluid sample to measure continuously both temperature .SIGMA.w of the said heat-generating element and fluid temperature .THETA..infin. during the cooling or heating of the fluid sample at one or several constant cooling or heating rates. An abrupt change in .THETA.w-.THETA..infin. value is detected to obtain the practical gel-point temperature of a characteristic gel-point temperature, which is defined as the extrapolated gel-point temperature at a cooling or heating rate of zero.

Abstract: Here is disclosed a method for measurement of viscosity change in blood or the like comprising steps of disposing a sensor including of an endothermic or exothermic element in blood or the like, stimulating blood or the like so as to cause a viscosity change therein and detecting the viscosity change by continuously measuring any one of changes occurring respectively in an average temperature .theta.w or a surface temperature .theta.s of the sensor containing therein the endothermic or exothermic element, a differential temperature .theta.w-.theta..infin. or .theta.s-.theta..infin. between a temperature .theta..infin. of blood or the like and .theta.w or .theta.s, a kinematic viscosity .nu. of blood or the like and a heat transfer coefficient on the sensor surface.

Abstract: A sensor used for electrical heating measurement comprises a sensor element having a rod, plural through holes provided straightly through the sensor in the longitudinal direction and plural metal thin wires inserted into and passed through the through holes and an electrically insulating member covering the sensor element, preferably the metal thin wires thinner than through holes are used, spaces around the metal thin wires are filled with ceramics powder and the powder is sintered by heating at lower temperature than the sintering temperature thereof.

Abstract: A method for measuring a surface temperature of a sensor being heat-transferably contacted with a subject fluid by employing an electrically heating method in which the surface temperature is measured while passing an electrical current through an electrical conductor included in said sensor. In this measuring method, the surface temperature is expressed as a function of a specific value inherent in the sensor, an amount of the electric current supplied to the electrical conductor, and a temperature of the electrical conductor. The sensor is heat-transferably contacted with another fluid whose physical properties are previously known, a surface temperature of the sensor contacted with the another fluid is determined by satisfying a relational equation between the physical properties of the another fluid and the surface temperature, and the specific value inherent in the sensor is determined by using the determined surface temperature.

Abstract: A sensor for electrical heating measurement has a core rod which is partly reduced in diameter to form an annular recess, an inner electrically insulating layer formed within the annular recess, a thin metal wire wound about the inner electrically insulating layer, an outer electrically insulating layer covering the metal wire winding and being flush with the outer circumferential surface of the core rod, and a metal sleeve being in intimate contact with the outer circumferential surface of the core rod throughout the overall length thereof.

Abstract: A sensor for measuring the temperature of a liquid or semi-solid material by electrical heating. A core rod has disposed thereon a first electrically insulating member and a thin metal wire is wound about the first insulating member on the core rod. A second electrically insulating member covers the thin metal wire. When an electrical current is passed through the thin metal wire heat is generated in the thin metal wire. The resistance in the thin metal wire is proportional to the temperature thereof, which temperature is proportional to the current passed through the thin metal wire and the temperature of the liquid or semi-solid in which the sensor with the thin metal wire is disposed. Thus the temperature of the liquid or semi-solid can be determined by measuring the voltage or resistance in the thin metal wire by known measuring devices.

Abstract: A method for automatic measurement and control in curd making process is provided wherein an electrical current is supplied to an electrical conductor thermally contactable with milk stored in a curd tank so as to be heated to result in sufficiently higher temperature of the said conductor than the surrounding milk, temperatures or electrical resistances of the electrical conductor are measured in relation to time lapse, an elapsed time starting from the commencement of curdling is measured on the basis of a change in temperature or electrical resistance of the electrical conductor, and the elapsed time is compared with a predetermined curdling progress time ranging from the commencement of curdling to curd cutting so as to automatically judge a curd cutting timing.

Abstract: A measurement method for determining the state of coagulation of raw milk in a production process for, for example, cheese or yogurt. According to this method, the state of coagulation of milk can be determined by placing a metal wire in the milk and, while feeding an electric current continuously or intermittently to the metal wire, measuring the temperature of the metal wire over a given period of time.

Abstract: Disclosed is a method for measuring changes in a physical property of a liquid or semisolid material which comprises placing a thin metal wire in the material; passing an electric current through the thin metal wire in such a way that the temperature difference between the material and the thin metal wire is kept constant; measuring the intensity of the electric current; and calculating the heat transfer coefficient at the surface of the thin metal wire on the basis of the measured intensity of the electric current and thereby detecting changes in a physical property of the material. This method makes it possible to detect, for example, changes in the coefficient of kinematic viscosity of a food having the form of a gel or changes in the condition of thrombus formation in a blood vessel.